Mary looked up as Barrow returned to the dining room, a silent question in her eyes. The butler shook his head slightly, and her heart sank.

'Is Mr Talbot safely abed, Barrow?' Robert enquired of his butler.

'He is in his bedroom, my lord, but he would not let us in with him. He threw me off and locked himself in the room. I left Mr Bates trying to reason with him through the door, but it seems he is determined that he needs no assistance tonight,' Barrow replied, glancing at Mary.

She bit her lip, frustrated that they would not be able to get the letter back tonight.

'Right, well, at least he is contained and can make no more mischief tonight. Thank you for your help with this unfortunate matter, Barrow,' her father said, ready to move on.

'Do you think he will be all right? He seemed to have consumed rather a lot of alcohol,' Cora said, more worried about her son-in-law than anyone else around the table.

'I'm sure he'll be fine, Mama. He'll sleep it off. Besides, if he's locked the door, there is little anyone can do to ascertain if he is all right, so if he's not, it's his own fault,' Mary said, not feeling in the least bit charitable towards her husband.

'I hate to think of him alone and ill up there,' Cora persisted. 'I know you have your differences at the moment, but surely you don't wish any harm on him, Mary.'

'Quite frankly, Mama, at this precise moment in time, I don't care if Henry falls headfirst out of the window in a drunken stupor. It would actually save me a lot of bother,' Mary said, crisply.

'Mary! You don't mean that!' her mother exclaimed, shocked by her daughter's callousness.

'Don't I?' Mary asked, quite unconcerned.

'I don't think we need to worry about Henry any further, Cora. If he needs assistance, he can call for it. Now, we will not speak of it again this evening,' Robert said, drawing a line firmly under the evening's shenanigans.

Mary waited until after her parents had retired for the evening before holding another council of war with Tom and Barrow.

'He didn't let Bates in then?'

'No, milady.'

'Do you have another key to your room, Mary?' Tom asked. 'Perhaps one of us could sneak in tonight while he is asleep.'

'And root around in the dark for the letter?'

'We could check his dinner jacket at the very least. It may still be in there.'

'Well, I don't have a key. It always remains on the inside. I do not feel the need to lock my room up when I leave it.'

'Mrs Hughes will have one on her set of master keys,' Barrow said suddenly. 'She leaves them in her office when she goes home at night.'

Mary stared at him, a smile spreading on her face. 'Barrow, I could kiss you!'

The butler pinked up, a small smile tugging at his lips at her praise. 'Well, should I go and fetch the keys then?'

'Yes, please. Perhaps we can put this business to bed tonight after all,' Mary replied, her spirits rising.

Barrow departed on his mission to get Mrs Hughes' keys, leaving Mary and Tom alone in the drawing room. Mary reached out for Tom's hand, tugging him closer.

'For all the unpleasantness of today, Henry's done us a favour, my darling. I'll be able to divorce him much sooner than I anticipated,' she said, sliding her hands up the front of his dinner jacket. 'And you know what that means.'

Tom smiled at her, wrapping an arm around her waist and pulling her against him. 'It means we won't have to wait much longer to begin our secret affair properly.'

'And thank God for that,' Mary murmured, closing the gap between them to kiss him.

Tom kissed her back, things becoming more heated between them as they stumbled backwards until they came up against the high back of the sofa. Mary groaned as he moved to trail his lips down her neck.

'How much longer do you think we will have to wait?' she murmured, tilting her head to give him better access. 'Please don't tell me you want to wait until the ink is dry on the divorce papers.'

Tom chuckled, making Mary shiver at the delicious feel of it against her skin. 'Well, it would be a sin until you are properly divorced.'

'I thought Catholics don't believe in divorce,' she said, slipping her hands under his jacket and up the sides of his torso, pulling an answering shiver from him.

'We don't, so I think we might as well be hung for a sheep as a lamb,' Tom said, pulling away from her neck to smile at her. 'The only condition I will put on it is that Henry can't be at Downton when it happens. If we succeed in getting the letter back, the last thing we need is for him to catch us in flagrante and give him more ammunition against you.'

'You are a very wise man, Mr Branson. It's a deal,' Mary breathed, hooking her finger under his chin to pull him in for another kiss.

This time, they didn't part until the sound of Barrow's footsteps echoed in from the Great Hall. Mary lifted a hand to wipe her lipstick from Tom's mouth before she stepped a respectable distance away from him, trying to calm the desire sizzling through her as Barrow arrived with Mrs Hughes' master key ring.

Mary and Tom waited somewhat nervously as Barrow selected the key for Lady Mary's room and tried to slot it in the keyhole. He frowned when he met resistance.

'I think the key is still in the lock on the other side,' he said, jiggling his key.

'Oh, for goodness' sake! Is nothing going to go our way tonight?' Mary hissed in frustration.

'Don't give up yet, milady,' Barrow said, producing a strange-looking penknife from his trouser pocket and unsheathing a long, thin blade.

'What on earth are you going to do with that?' Mary asked, curiously.

'I might be able to wiggle the key out on the other side,' the butler told her, kneeling down and inserting the blade into the keyhole.

'My, Barrow, you have hidden talents. You're a good man to have onside in a crisis,' Mary said, impressed with the butler's ingenuity and tenacity. Several minutes later, she looked up at Tom in triumph as they heard a soft thump on the other side of the door. 'You've done it! I think you've done it! Have you done it, Barrow?'

'I believe so, milady,' Barrow said, rising to his feet with a smile. He slid the key in the lock and turned it, his smile turning into a grin as the lock disengaged.

'Oh, Barrow, you are a genius!'

'Thank you, milady, I do try. Do you want me to be the one to go in there?'

'No, I'll do it,' Mary said quickly, not wanting to run the risk of the butler getting an eyeful of the rather racy contents of the letter.

'No, Mary, I'll go,' Tom said, putting his hand out to stop her. 'I don't want you in there if he wakes.'

Mary rolled her eyes. 'I can hear him snoring from here. He won't wake. And if he does, he'll be less suspicious if he sees me in the room in the middle of the night than you.'

Tom bit his lip, mulling that point over, knowing it made sense but still uneasy about the whole affair.

'Besides, you and Barrow will be right outside the door if I need rescuing,' Mary said, taking hold of the door handle.

'All right, but be careful,' Tom said, reluctantly giving in to Mary's logic and determination.

She flashed him a brilliant smile and pressed down the handle, opening the door and stepping inside her bedroom. The light from the corridor cut a swathe across the top of the room, allowing her to see something of the lie of the land.

Henry lay sprawled on his front on top of the bed, still wearing his black-tie formalwear. Mary sighed softly in irritation. If only he'd stripped off before collapsing into bed, this would have been much easier but, of course, Henry would make this difficult, even unconsciously.

She approached the bed, assessing the situation and considering how to get him to turn over. She could try and manhandle him, but she doubted she'd be able to manage his deadweight by herself and she didn't want Tom or Barrow in here if she could help it. She stood by the bed looking thoughtfully at her husband snoring gently. Finally, she settled on the easiest option.

She steeled herself and lay on the bed next to Henry, nudging up against him.

'Budge up, darling. You're taking up all the room,' she said in a low voice.

Henry stirred without really waking up, shifting a bit to give Mary more room, but not quite turning enough for her to reach the pocket she needed. She rolled her eyes in irritation, wrinkling her nose at the strong smell of stale whisky wafting off him.

'Mary,' she heard Tom whisper from the doorway as he stuck his head around the door to see what was happening.

She frowned at him, waving him away, worried he might wake Henry. Tom stared at her, his mouth dropping open as he saw her lying on the bed next to Henry. Mary waved her hand again, shooing him out of the room, but Tom shook his head, refusing to move.

Mary decided to ignore Tom hovering anxiously in the doorway and concentrate on her mission. She snuggled up closer to Henry, pushing at him to try to make him move. This time, she got her reward as Henry rolled over onto his back, moaning slightly as he did so.

Mary smiled, sensing victory. She waited a few minutes until Henry settled and started snoring again before raising herself up on her elbow and leaning over him. She peeled back the front of his jacket, fishing in his inside pocket, feeling an envelope. Slowly, carefully, she withdrew it, feeling a great sense of relief as she saw the familiar M in Tom's script on the front of the envelope.

Now, it was time to make good her escape. Mary lay flat again and inched across the bed away from her husband, trying her best not to disturb him. She nearly made it, but as she got close to the edge of the bed, Henry rolled onto his side, flinging his arm heavily over her waist and pulling her back towards him.

'Mary,' he murmured. 'You're here.'

Mary scrunched up her face, rueing her luck. 'Of course, I am. Where else would I be?' she whispered as sweetly as she could.

'Hmmmm,' he said, nuzzling his face into her neck.

Out of the corner of her eye, Mary saw Tom take a couple of steps into the room. Swiftly, she held up her hand to stop him. He halted, but she could see he wasn't happy, could practically feel the anxiety radiating from him.

Henry snorted, his breathing deepening again. Mary waited for what felt like an eternity but was probably only a minute or so before edging away from him again.

Once more, she nearly made it before Henry moved again, his hand tightening on her waist.

'Where're you going?' he mumbled.

'I need the lavatory,' she whispered. 'I won't be a minute, darling.'

'Hmm,' Henry muttered, loosening his hold on her. Mary slid off the bed, clutching her prize as Henry's hand thumped onto the mattress where she had been. She turned to look at him as he buried his head into a pillow and started snoring again.

'Mary!' Tom hissed from the doorway.

Mary took a few steps backwards, keeping her eyes on Henry then turned and fled, Tom ushering her out of the door and pulling it softly shut behind him.

'I got it!' she whispered, holding the envelope up in triumph.

Tom broke into a grin, catching her up in a hug and twirling her around. Mary flung her arms around him, laughing softly, still clutching the letter. Barrow watched them, a curious smile on his face.

Mary caught sight of him and realised their behaviour was inappropriate, even if Barrow was part of her secret army of helpers. She tapped her hands on Tom's shoulders, and he put her down, perhaps also realising they were being indiscreet.

'Shall I lock the door again, milady? It might give him pause in the morning if he has to unlock it himself. He won't know what's happened.'

'Yes, that's a good idea, Barrow. Do you know, I am gaining a greater appreciation of the Machiavellian elements of your nature by the minute,' Mary said, approvingly. 'Thank you for everything you've done over the last few days. I can't tell you how grateful I am. I will not forget your loyalty.'

'That's quite all right, milady. I'm happy I've been able to help.'

'And, now, I think Mr Branson and I might have a nightcap to celebrate the successful outcome of our plan, but you should retire for the evening, Barrow.'

'Are you sure, milady? I don't mind serving the drinks.'

'I'm sure. You've earned an early finish tonight. And we might need to be alert for whatever mood Mr Talbot will be in tomorrow.

'Very good. I'll wish you good night then, milady, Mr Branson,' Barrow said, nodding his head at them.

'Good night, Mr Barrow,' Tom said, nodding back, grateful to the butler for his help.

'Good night, and thank you, again,' Mary said, smiling at Barrow before turning to go back downstairs, Tom following behind her.

Barrow turned to quietly insert the key in the door and lock Mr Talbot back into Lady Mary's room.

In the library, Tom poured them both a whiskey as Mary stood waiting for him in front of the fire. He came over and handed her a drink, raising his glass in a toast.

'To a job well done.'

Mary clinked her glass with his. 'I had my doubts at times, but it all worked out in the end.'

'I had my heart in my mouth when he slung his arm over you. What on earth made you get onto the bed with him?'

'I was banking on him being drunk enough and sleepy enough to forget we were warring and just behave as he normally would if I got into bed with him,' Mary said, with a shrug. 'That was the simplest thing I could think to do to get him to turn over.'

'And it worked.'

'It certainly did,' Mary said, holding up the letter that had caused all the trouble.

'And now we burn it,' Tom said with some satisfaction.

Mary hesitated. 'Do we have to?'

He looked at her, surprised she would even think about not burning it. 'Of course, we do. We can't run the risk of him getting his hands on it again, otherwise all of this will have been for nothing.'

'I could just tell him I've burnt it,' Mary said, hopefully.

'Or we could just burn it,' Tom said, firmly. Mary looked at him imploringly. 'Don't look at me like that. We need to burn the damn thing and you know it.'

'I don't want to,' she whispered.

'Why on earth not?'

'Because… because it's the first letter you've ever written to me,' she muttered, blushing a little.

'That's not true. I wrote to you all the time when I was in America.'

'Not like this, you didn't,' Mary said, feeling a bit self-conscious. 'And we weren't... well, you know, when you were in America.'

Despite himself, Tom felt a smile tugging at his lips. 'Mary, are you getting all sentimental on me?'

'Maybe. But so what if I am?' she retorted, feeling a bit embarrassed about her attachment to the letter.

'I can write you a thousand letters if you want me to after Henry's out of the picture,' he said, fondly. 'But we have to burn this one.'

'But it's the first one. And it's so… so…' she cast around for the right words as Tom raised a curious eyebrow, 'delightfully dirty.'

He grinned at her. 'Well, I'll write you more delightfully dirty letters, I promise. But if you love me like you say you do, you'll burn this one, so I don't go out of my mind worrying about Henry getting his hands on it again.'

'Oooo, that's low, Tom. That's like blackmailing me to do what you want,' Mary said, indignantly.

'Maybe so, but I'm right and you know it.'

Mary subsided, knowing he was right and they had to burn the letter.

'I'll burn it if you like,' Tom offered, holding out his hand for the troublesome letter.

Reluctantly, Mary handed it over, watching as he stepped forward and dropped the envelope on the fire. He moved back beside her and slipped his arm around her waist. Mary leaned into him, resting her head against his as they stood together and watched his words burn.