"I don't care what the official line is," Robin Wellesley says just as she sets an empty cup on its saucer. "She disappears for months and then the day she gets home, she's no longer a nun. Two weeks later, she's engaged to the Doctor. Mark my words, they were having an affair and the nuns sent her away to try to turn her off him."

Without missing a beat, Laura McAvoy slips in, "Or to cover up the results."

Around the kitchen table, of the eight other women present, one snickers and nods, two let out a shocked and unexpected gasp (only one remains unconvinced after the initial shock), two others frown in uncomfortable disapproval, and only Molly Henderson tries to keep a neutral expression.

Molly ducks her head and sips her tea as one of the shocked women asks, "You think she was having a lie-in?"

Mary Chaplin shakes her head. "That doesn't make any sense. If she'd gotten pregnant, where's the baby?"

"She would have given it up," a heavily pregnant woman beside Molly suggests.

"Of course she would'of," Laura, who'd started this speculation, agrees.

Mary pursed her lips and shook her head. "Gave up the baby and then left the order and got engaged?"

"What order was she supposed to do it in?" snapped Robin, who was the first to suggest the affair. "This way, it seems like she left the order to get married. If she'd shown up with an infant to get engaged, well, that'd make it too clear."

"No, I can't believe a man would go after a nun," the pregnant woman (a Mrs. Neil who was fairly new to Poplar) said while shaking her head. "Not like that. Not enough to get her into trouble. I'll believe the nuns sent her away to get her head on straight, but not that she was in any trouble."

And that declaration splits the table into three conversations: one between Robin and two others, who were now convinced of a sexual affair and trying to pin down how long it had been going on before they were caught; another between Laura and Molly, in which Laura wonders how they'd kept it so well hidden and is trying to coax her less willing partner into remembering any sign of impropriety; and the last between Mary and Mrs. Neil, who were so convinced that nothing had happened they begin alternating back and forth with loud exclamations of Sister Bernadette's and Dr Turner's innocence.

It's nearly an hour later before everyone tires of the Sister Bernadette-Dr Turner scandal and exhausts all other conversation. Molly Henderson excuses herself first and walks the long way home, happy for a few more moments of peace to think.

The conversation at tea had upset her. Not because she placed Dr Turner or even the Sister on any pedestal – she knew they were real people with lives beyond their medicine – but because, while the other women were just gossiping about nothing, Molly had begun to think she knew the real story, because Molly had witnessed four events that the other women did not. Four moments that, at the time, had been meaningless and, as memories, had gone unconnected.

It was almost a year ago to the day, she realizes, that she had been at the clinic when she watched the little nun – Sister Bernadette – blush. She remembers the blush vividly because, for the first time since she'd met the little nun eight years prior, she had never really noticed anything particular about her. It had always been hard to think about the nuns as women – as women with pretty hair and soft faces hidden beneath those habits. But when the little nun blushed, she turned a smooth, delicate pink from her cheeks to the edges of the wimple and down what little of her jaw and neck were exposed. It was the first time Molly realized how young the little nun was. Younger even, quite possibly, than Molly herself.

Now, it suddenly occurs to Molly that she had been so entranced by the blush that she had entirely neglected the cause.

They were at the Tuesday clinic. Molly was sitting, waiting for one of her final checks with Sister Evangelina when she looked over to see Sister Bernadette standing in the doorway to the back room. She was holding a fairly heavy looking crate filled with glass containers. Some of the glass bottles came up to her nose and the glass was rattling against each other as the little nun struggled to look up over the crate and watch where her feet took her. After an uncertain step or two, Dr Turner appeared from seemingly nowhere and quickly relieved her of the crate. Molly was pretty sure his hands grazed the little nun's as he took over the crate. That was when the blush began, just visible on the highest part of her cheeks. Then their eyes met. And the longer she looked at him, the more her reserved smile brightened in her eyes. It wasn't until she looked away and the Doctor walked off with the crate that the blush spread across her face, as if the first little blush was arousal and the second shame.

What was that moment, she wonders, in light of everything that's happened? Was it the first bloom of love? The little nun suddenly seeing a man as a man, suddenly realizing a yearning for something behind service to God? Was it shame or guilt or embarrassment that Molly saw in that final moment and was it that conflict between want and self-denial that made her chose to go away?

Or was this something else, something more… Had the affair already begun by then? Was the Doctor's hands grazing the little nun's pure accident, or was he already familiar with the texture of her skin? Was it a flirtatious, daring stolen moment that made her blush in memory of the night before? Was the final, encompassing blush a flare of passion and memory?

Molly can't say which it was, but she has a hunch that it was an early incident in the little nun's and the Doctor's liaison. She would bet money that, before that incident, there had either been nothing more than an unconscious interest on both sides or there had been something more forward – lingering stares, late-night talks, chaste moments of tenderness – but nothing untoward. She suspects that now because of the second memory suddenly brought to mind.

The second memory occurred only about two weeks or so later – Molly remembers because her little Eileen was overdue, should have been born a week after the blush, and the discomfort of being so large and tired and hot had drawn her out to pace in front of her flat's door. It was the start of spring so, even though it was already fairly late and the street was pretty quiet, there was still enough light to see a young woman ride past. Molly remembers this moment clearly because the bike was certainly one of the Nonnatan's – it had the leather case mounted to the back the nurses' used to carry their medical bags – but the woman wasn't one of the nurses; at least none Molly had ever seen and she felt she'd been around enough the past few months to know.

It was that curiosity that made her watch the woman halt rather determinedly before the Doctor's door (Molly lived just across the street, three doors down from Dr Turner, which she always felt gave her a great deal of peace of mind, especially as she neared the end of another pregnancy). The woman was slight, shorter than Molly, and the clothes she wore seemed a little too big for her frame, like they were handed down and not bought or made for her.

Molly watched the woman stand straddling her bike, staring at the Doctor's door for a few minutes. She couldn't see her face and so couldn't decide if she was trying to read the number in the dark, confirming she'd arrived at the right place, or was just trying to make up her mind to knock. Finally, the woman parked the bike up under the Doctor's parlour window and made two sharp knocks on his door, so sharp even Molly across the street and three doors down could hear her knuckles against the wood.

It was the Doctor who opened the door. Molly thought he looked shocked, but recovered himself well. They only exchanged two or three short sentences before he seemed to invite her inside. Just before she entered, the woman turned and looked down the street. For just a brief moment, Molly thought the woman looked like the little nun – same glasses; similar size – but Molly couldn't quite entertain the thought that the little nun had golden hair and such a strong jawline or high cheek bones. At the time, she laughed away the thought of the little nun stealing out of the covenant in lay clothes to be secreted inside Dr Turner's house.

It was such a silly thought then, but now…

Now Molly wonders whether it could have been her. What could convince such a pious little nun to sneak off in the middle of the night, to enter a man's house under such strange circumstances? What might have been the result of that night?

When the door opened, Dr Turner would have looked down on this slight woman. He would have recognized her instantly; Molly's certain he would have looked down into her blue eyes and known her. But then he would have wondered what she was doing on his doorstep so late. Then he would have noticed her clothes, her loose hair, and he would have wondered what had happened.

"Sister Bernadette?" he must have said, confused, curious.

"Is Timothy home?" Of course that would have been her first concern. She was such a practical woman and intuitive. She wouldn't have entered his home in such a foreign, dangerous state if there'd been a child in the house.

Absently, Molly recalls that Timothy wouldn't have been there. Her Jimmy was gone that night too, off on an overnight with the cubs, and Timothy Turner must have been with them. Dr Turner probably said as much and, as soon as she was assured he was alone, he would have invited her inside. When she glanced behind her, surveyed the street, was that hesitation, second-guessing her decision? Was it a guilty consciousness, hoping to minimize her presence? Molly suspects the former.

Once inside his home, what must the little nun have thought? Perhaps she inspected the parlour, spied inside the kitchen, drank in this hidden, private world of the man she was beginning to love. Did she imagine herself living there, imagine herself as Mrs Turner – a different life, a different woman?

And the Doctor, he must have invited her in, awkward and wary of what this night held. Would he have offered her a cup of tea, a seat, or would he have stood, just inside the hall with his hands tucked in his pockets, wanting to reach out to her, but resisting with every ounce of control, desperate for answers but without the words to form his questions.

The little nun would have begun:

"I needed to talk… I needed to talk without feeling as if every thought or feeling was inappropriate. To talk as if I had no vows to break."

Where things went after that is where Molly is at a loss. What does a man say to a nun to lure her into bed? What does a nun out of her habit think and feel?

Molly imagines that Dr Turner had been avoiding looking directly at the little nun ever since she entered his home, but as soon as she said "no vows to break," he must have taken that as permission to look at her, to really look at her. To see the woman who had been hiding beneath the habit. See the creamy, untouched skin on her neck; imagine the sharpness of her collarbone through the blouse; notice the way the pale blue material clung to her breasts, the navy skirt accentuated her soft curves; admire her exposed calves, the paleness of her skin.

His would be the kind of gaze she hadn't experienced since she'd become a nun, perhaps ever. Would that have made her withdraw, become shy before him? Bow her head and blush. Lose her nerve to say anything further.

No, certainly feeling his gaze – feeling desired; knowing her interest was reciprocated – would have reaffirmed her decision and made her bolder.

Sister Bernadette – or perhaps it's easier to think of her as Shelagh; Molly heard somewhere she goes by that name now – Shelagh blushed but maintained eye contact. "I think about you as I fall asleep. I dream about you." She pauses, bites her lower lip.

Perhaps that's all it took. Sometimes there aren't words, just desires and half understood motives. She imagines Shelagh closing the distance but the Doctor making the first effort to reach out. Would he have run his hand down her arm, keeping some distance between their flesh? Or would he graze his fingertips along her cheek, down her jaw, perhaps resting on her exposed neck? That would have been the spark that made the little nun look up, inhale his scent, and wait for his lips to descend upon hers.

The kiss would have begun soft and gentle – so much unsaid and uncertain between them and her so inexperienced – but in a moment, the Doctor's hand came to rest on the back of her neck, the other slipped around her little waist, and suddenly the proximity, the heat of her body against his, the mixture of shock and reality would have shattered the dam of long repressed desire.

Then, as if they were awake alone in their cold beds, the rest played out like a fantasy.

There was just a murmur of a nagging voice in the back of Shelagh's mind. Just loud enough to hear over the hum of her arousal; just insistent enough for her to attend to absently as the Doctor's lips pepper her jaw with soft kisses. It reminded her of a vows, of her duty to God, of her sisters, of her vocation. It was exactly the voice she had sought to avoid by removing the habit. It was precisely the voice she had silenced the moment she stripped in a private hallway in Nonnatus House, before hastily donning on borrowed clothes from the charity clothes and slipped out into the night, and again the moment before she dismounted her bike and rapt on his door. As his lips burned a trail up her neck and to the base of her ear, she dismissed it again. She let herself be consumed by him. There was a fire within her that burned from her cheeks to her toes, casting every bit of pale skin a shade of pink so alluring there was no hope for the Doctor to regain control of his senses.

There must have been a voice screaming out in his mind telling him to stop, one that reminded him she was a nun. But then his eyes would scan her over once more – the golden hair falling in gentle waves around her face, eyes dilated with arousal, clothes that clung to her, that exposed her as a woman – and in his state he couldn't believe his own mind. And then there must have been a second voice, a determined sharp voice, that said if she wasn't a nun, she still wasn't his wife, she wasn't even his finance, she wasn't even his in any proper way. But by then he'd paused for so long, holding her, looking at her, not so much paralyzed by his conflict but in shock that she was there at all, and so Shelagh took charge by grasping the loose material of his shirt and using it as leverage to reach up and reclaim his lips.

It seems like the moment a man tried to lead a nun up to his bedroom, it would break the spell.

What if he had said something? A fumbling, "Do you want to go upstairs?" or "Should we go to my room?" Would that have shaken her resolve – the last chance to stop; the crushing reality of what she was consenting to do? Or would there have been something alluring in those words that made her feel finally in control of her own mind, something that made this not an act of disobedience but an act of rediscovery.

Or maybe he would have been too heated to say anything and too nervous about the possible ramifications. Perhaps he just carefully disengaged, took her hand, and led her to his bed with the confidence that every man has with a willing woman.

Perhaps this is when the timid virgin would reveal herself. The little nun standing just before the foot of his bed, her hands trembling as she unclipped her skirt and let it fall to the floor in a pool of navy covering her feet. And then the blush that covered her skin. Her eyes looking from a knot on the hardwood floor to a pastel flower petal on the wallpaper and finally to her delicate fingers stumbling to undo the third button on her blouse.

Or would this new-found control, new-found freedom have made her commit fully and become something of the seductress? Just inside the Doctor's room, would she have raised up to kiss him and, at the same time, unbuckled his belt. Every man is aroused by the slow release of their trousers' fly, but would the Doctor have been unusually so, both impressed and intrigued by her forwardness.

However they had managed it, they would eventually have fallen naked in bed together, touching each other, exploring. It must have been at least a little reassuring for the little nun to be so well aware of what the act entailed, even if just from a clinical perspective. Did that make her more or less nervous when he eventually placed his body over hers and entered her?

Would they really have slept together, she wonders, a nun and a Doctor who know the results of such an act better than anyone and who, more than anyone, would be destroyed by such a mistake? Molly really can't say. She knows (because she couldn't sleep all night) that the bike, which appeared around nine in the evening, disappeared sometime between two and four in the morning. Perhaps the little nun (if it even was her) was simply waiting for Nonnatus House to be asleep before she crept back into its halls.

What Molly does know is that two months later she was back at the clinic with little Eileen when she spied the little nun try several times in vein to take a sip of her tea, but every time the cup came within sniffing distance, she turned a little pale and the corners of her lips turned down in disgust. Finally, after the fourth or fifth try, the little nun hurriedly set down the cup, apologized to Nurse Lee, and dashed (with rather a great deal of poise) for the toilet.

No one else seemed to notice the little nun's distress and so Molly left little Eileen under a friend's watchful eye and popped into the loo after Sister Bernadette. When she arrived, there were clear sounds of vomiting and so she took a few paper towels, dampened them, and stepped inside the stall to place the cold against the sister's neck. For just a moment, Molly hesitated, but then crouched down and rubbed her back until the vomiting subsided.

When she was done, the little nun sat back onto her heels, twisted, and then collapsed a little against the stall's wall. She took the cold cloth from her neck and dabbed her forehead and mouth. Molly looked her over then. She suspected that the little nun had ripped off her wimple in a rush to get it out of the way because now it lay a bit disorderly beside the toilet's base and her little cap was on but slightly displaced so that some of the nun's golden hair had come loose and fell about her ear.

"Are you all right, Sister?" Molly remembers asking.

The little nun just pursed her lips and nodded. "Thank you," she said eventually, holding up the cloth briefly as if to thank her more for the paper towels than the concern. "There must be a little something going around," she said after a moment.

Molly nodded and, to try to help lessen her embarrassment, mentioned, "I think a few of my little Jimmy's classmates have come down with a little stomach bug. Perhaps I should ask the Doctor to pop in?"

Some colour returned to the little nun's face at the mention of the Doctor – a coincidence? It was hard to tell now.

"No, no. I'm perfectly fine." With that, the little nun reached for her wimple and pulled herself back onto her feet. "Thank you, Mrs. Henderson, you've been very kind. I wouldn't want to keep you."

Molly knew when she'd been dismissed and she left to give the little nun the privacy she wanted to tidy back up.

There had been a few boys with a little stomach bug then, but Molly had discovered a few days later that it wasn't so much a virus as much as it was a rather large stash of pilfered sweets too quickly enjoyed that had been the cause of everything. But still, a little stomach flu hits everyone now and then. Perhaps it was nothing.

But the more Molly thinks on the sight of the little nun without her wimple, the more she sees the face of the woman on Dr Turner's doorstep and the more she's certain it was the little nun in lay clothes who had come to see him that night. It's possible she had gotten herself in a fix. It's possible that she simply ate something that disagreed with her.

There's only one other moment and she's much less sure about what she heard and what she saw.

It was the day of the summer fete, not more than a few weeks after that incident. She popped into the clinic to use the toilette and, on her way out, she heard:

"At this moment, I only know that I'm not turning my back on you because of you, but because of Him."

If tears had a voice, they'd sound the like wavering of the little nun's voice. The pain froze Molly in place; she couldn't see the little nun, but they must be nearby. Then she heard in reply:

"And if I didn't understand that, I wouldn't deserve to live."

The voice belonged to Dr Turner, but the emotion was so foreign Molly couldn't begin to speculate. Was that guilt, sorrow, resignation? Perhaps it was all three.

She heard a rustling that she was confident meant one of them had left. And then the little nun began to cry, the kind of heavy sobs that didn't bring tears so much as frustration. Molly didn't know what to do. She didn't want to move and reveal herself. She wanted to comfort the little nun, but she knew she had encroached on something private – something confusing – and thought better of approaching. Then the little nun started moving around. Molly heard the tab shut off, a dry sob, a damp cloth slapped against the porcelain, a deep breath, and then the hurried, purposeful steps of the little nun leaving.

While Molly knew she'd witnessed something strange and private and difficult, she'd never had any context with which to understand those words or the little nun's crying. Never ever the foggiest hint of clarity. Until now.

Now suddenly she sees the entire exchange in a widely new context. At about three months after their possible tryst, this would be the moment when a knowledgeable mother would tell her lover she was pregnant. The little nun was so slight she had to know that she wouldn't have long before she would start to show. And how difficult it would be to hide from a house full of midwives. This was certainly the moment she told him.

In the noise of the three-legged race, they must have snuck into the clinic unobserved. Perhaps he had embraced her, kissed her, giddy with the excitement of the entire afternoon. (Could a man's lust and desire really ignore the habit? Perhaps his love could blind him.)

How would the little nun have begun that conversation? Molly remembered telling her Arthur for the first time. She'd been nervous – a bumbling fool who didn't have quite the right words. She'd stumbled over reminding him of their first act (not their only) and left her words hanging, drifting in the air. She and Arthur weren't married.

Was Sister Bernadette quite so awkward? Perhaps their medical language made it easier. Or perhaps her habit had made her more a fool than Molly's youth had.

She either prevaricated – wrung her little white hands and bit her lip, eyes casting about the clinic like they couldn't settle anywhere, all the while Dr Turner was waiting, hands thrust in his pockets, to find out why she'd lured him away from the festival – or she'd been forward – looked at him as soon as they knew they were alone, set her face and spoke:

"I'm pregnant."

When Molly had told Arthur, he went completely silent, so silent his face had gone blank and cold, so silent his body language had pulled away from her. Did the Doctor pull away from her, become so physically distant the little nun feared she was about to undergo this beautiful journey terrifyingly alone? Or was the Doctor more like her Arthur an hour later, when her simple, wonderful man had had a chance to digest and think, he came to her with that serious look in his eyes, but a spark of excitement and joy. It wasn't quite how they wanted it to go, but they weren't any less happy with the end result.

But how could the poor Doctor have felt that way? You had to love a nun to get her in a fix, but you also had to know, as soon as she told you, that an engagement ring couldn't make it right.

Molly imagines that, as a doctor, his first reaction was to ask what her symptoms were, whether she'd gotten tested, and so forth. He must have been trying to diagnose her with his eyes through her habit. She also imagines that, as a man, his first instinct was to ask whether she was certain, whether she planned to keep it.

Molly thinks almost certainly their initial conversation was more medical than she could re-construct – it would be easier for people like them, she thinks, to talk about the facts and the symptoms, the dates and numbers, than to actually talk. She rather envies them for that.

But eventually they would have stood before each other, a little nun with her habit hiding everything but the fear in her grey-blue eyes and the Doctor with his hands shoved into his pockets to hide their shaking, and actually addressed the real problem: how could a nun have a child? How could she leave the order that moment, marry him, and have a child? It could happen only if they left Poplar and everyone in Poplar knew that the Doctor and the Nuns loved Poplar too much, were too devoted to their work, to ever leave. So there was only one option, wasn't there?

"I can't keep this child," the little nun must have said. She must have known this.

The Doctor must have nodded. He would have thought of this as well. Or did he protest? "I can marry you. I will marry you."

Is that what he said? Molly had no doubt he was a gentleman, despite his possible impropriety. He must have said at some point.

"I can't… I can't keep it and we both know that."

"What will you do?"

Did either of them even think to discuss getting rid of the child? If anyone, the Doctor could have arranged for a medically necessary abortion. It could have been arranged, privately and clandestinely. But Molly hoped he was too good of a man to suggest it and she was too much of a good woman to have asked.

"I'm going to have to tell Sister Julienne."

"We're going to have to tell her." Would the Doctor have stepped forward then, took her hands in his, held her near him, promised with his gestures alone to walk beside her?

Or was he more recluse? Were they beginning to pull away from each other? Would he have even offered to be a part of her reveal if they hadn't been holding one another?

"They can send me away for a while, go into seclusion until… after."

"Keep it a secret, you mean?"

What kind of secrets were hidden behind the walls of convents? Certainly the little nun wasn't the first to ever fall pregnant.

Molly can almost hear the Doctor's voice – that same heavy tone, that unknown emotion – say the words: "And then what?"

And then what exactly. Molly could imagine precisely what the little nun must have been feeling – she'd gone briefly through some of those very questions in the hour Arthur left her. How can I grow this life inside of me – something that is a little of me and a little of a man I love – and give it away? How could it possibly live a better life with someone else, someone not me?

But how much more weight was in the question for them – and then what…

After the child, would she return to Nonnatus as a nun? Would her life keep moving forward as it always had? How could a nun give birth to a child and stay a nun? How could her sisters know she had given birth and not shun her?

And what of the Doctor and their relationship – what was their relationship? No nun gives up her virtue without loving a man, or at least loving the idea of a man. Would she give him up, could she give him up?

The Doctor's (imaginary) questions echoes in Molly's head: "And then what?"

"The child is given a home."

"I meant with you. With us. Then what happens?"

"There shouldn't have been an us. Once I leave, I won't be allowed back."

Perhaps he would have gone quiet, serious, like exhaustion tempering an argument. His voice – resigned, demanding: "Then chose to come back."

Or would he have been passionate, becoming animated at her obedience? Would he have stepped up to her, embraced her, pleaded with her: "Chose to come back. Chose me."

Or perhaps he was silent. Was he holding everything behind a thin veil of composure? Had his face tensed, his lips pursed in an effort to hold his desperate plea in?

Whatever he said or didn't say, she must have known what he wanted, but she couldn't give it to him.

"At this moment, I only know that I'm not turning my back on you because of you, but because of Him."

"And if I didn't accept that, I wouldn't deserve to live."

He left almost as soon as he spoke. A year later, she finally felt the full pain and torment of those words the Doctor spoke. In one sentence, he gave up the woman he loved, his unborn child, and any right he had to possess either of them all out of respect for her – her reputation, her faith, her dignity.

Finally, Molly has made it home. As she stands in front of her flat's door, she turns and looked across the street three doors down at the Turner residence. No one seems to be home, but as she looks at the blue door, all she can think about is the determined young woman being ushered quietly into the Doctor's house that night.

Maybe that young woman had been Sister Bernadette, maybe it hadn't been. How could she know? She was half-delusional with pregnancy and exhaustion. Maybe there hadn't even been a woman.

Maybe there had been a child and the poor little nun had had to give it away. She'll never know that little babe; she'll spend her life wondering who this child became. Molly couldn't imagine giving up little Jimmy but then later marrying Arthur. She would have always seen Jimmy in Arthur's face; she would have seen him in every new child. She hoped, she prayed, she decided that there had been no affair, no secret tryst one spring night, no child. There was just love that had discovered itself and she was happy for them.