'So, he'll be leaving tomorrow then, will he?' Anna asked as she dropped the necklace carefully over Mary's head.

'He will if he knows what's good for him,' Mary said, glancing at the door in the mirror as someone knocked on it. 'Anna, see who that is. If it's Mr Talbot, tell him to go away.'

Anna nodded and crossed to answer the door. She opened it to find Tom Branson outside, Barrow behind him.

'It's Mr Branson and Mr Barrow, milady.'

Mary turned on her stool, wondering why both Tom and Barrow were at her door. 'Let them in, Anna.'

Anna pulled the door wider, allowing the two men to enter the room.

'Henry wants to see us,' Tom said without preamble.

'What? Why?'

'I don't know. He sent Mr Barrow to fetch us.'

Mary switched her gaze to the butler. 'Did he indeed? What did he say, Barrow?'

'He said to tell you and Mr Branson to come to the library before dinner, milady.'

'And how was his manner? Contrite? Combative?'

'Neither,' the butler replied, thinking about it. 'He was very calm. I'd even say confident. He said he had something to discuss with you both.'

Mary exchanged a look with Tom.

'What do you think he wants?' Tom asked, trying to anticipate whatever it was they may be walking into.

'He's no doubt going to try to wheedle his way out of the situation he finds himself him. He's good at that,' Mary said, wondering what her husband was up to. 'But it won't do him any good. Not this time.'

'What would you like me to do, milady?' Barrow asked. 'Should I tell him you're not coming?'

'No, that would only inflame the situation,' Mary said, thoughtfully. 'We'd better go and see what he wants. Better to know what he's thinking than to give him the chance to make mischief unchecked. Keep your enemies close and all that.'

Tom chewed his lip. 'I've got a bad feeling about this, Mary.'

Mary sighed. 'We should have guessed he wouldn't go quietly into the night, Tom. We'll just have to weather whatever he thinks he can throw at us in an effort to change my mind.'

'Is there anything we can do, milady?' Anna asked, ever ready to assist her mistress.

'I don't know yet. I won't be in a position to ascertain what, if anything, needs to be done until after he's made his case or whatever it is he intends to do. But I may need your assistance later, both of you,' Mary replied, looking between Anna and Barrow.

'Yes, milady,' they said in unison.

'Right, let's go and see what he wants then, Tom,' Mary said, rising to her feet and pulling on her evening gloves, readying herself for battle.

'Ah, there you are, darling. How beautiful you look this evening. Quite the picture of the lady about town,' Henry said, a drink already in his hand. 'And, Tom, good of you to join us.'

'What do you want, Henry?' Mary asked, cutting right to the chase.

Henry looked over at the butler, who had followed Mary and Tom into the library. 'Barrow, could you fix Lady Mary and Mr Branson a drink and then make yourself scarce, there's a good chap.'

Barrow glanced at Mary who gave him a slight nod, then set about making their usual choice of drinks.

'What do you want?' Mary said again.

'Oh, don't be like that, my love. Anyone would think you're not enjoying this little gathering. As it happens, I do have something to say, but I think we should wait until Barrow has departed,' Henry said, wafting his glass in the butler's direction. 'There is already at least one person too many involved in our marital matters as it is. I'd rather not increase that number.'

Mary narrowed her eyes at him suspiciously, accepting her drink from Barrow, who handed Tom his glass of whiskey then headed for the door.

'Close the door after you, Barrow, will you?' Henry called.

The butler paused, glancing once more at Mary, then left the room, pulling the door shut behind him.

Mary turned to Henry. 'Well?'

Henry smiled pleasantly at her. 'I've been thinking about your little ultimatum to leave Downton tomorrow and no longer darken your door, and I don't believe I will be doing that after all.'

Mary glared at him. 'I think you will.'

'No, my darling, I won't. Not with the information that has lately come to light.'

'What information?' Mary asked, fixing him with a sharp look.

'Information that confirms you lied to me.'

'I most certainly did not.'

'Ah, but you did. In fact, you told several great big whoppers.'

'And what, pray, did I lie about?' Mary snapped, indignantly.

'About him,' Henry said, pointing at Tom, who stared inscrutably back at him, saying nothing. 'And you.'

'What are you talking about, Henry? I don't mind telling you that you are sorely trying my patience,' Mary said, setting her cocktail glass down and crossing her arms.

'You told me he had never tried to get you into bed. You told me he had never made overtures to you. But that was a blatant lie, wasn't it?' Henry said, his eyes narrowing in anger.

Mary stared at him, a horrible thought entering her mind.

'Don't even try to deny it, Mary, because I have the proof.'

'Henry,' Mary began as Tom looked at her in confusion.

'Yes, you've slipped up, haven't you, my love?' Henry said, a spiteful glee colouring his voice. 'You've slipped up rather badly.'

'Is somebody going to tell me what you're talking about?' Tom asked, feeling his temper rising already.

'Oh, come on, Tom. You know exactly what I'm talking about. Your seduction of my wife.'

Tom looked at him, bewildered. 'I have never tried to seduce Mary.'

Henry raised his eyebrows. 'Well, I can't see how you can say that with a straight face, but you do look genuinely perplexed. Which I don't understand but let me tell you a story. Paint a picture if you will.'

'Henry,' Mary said again, but he held up his hand, waving her to silence.

'No, Mary, Tom needs to know how very screwed the two of you are, if you'll pardon the pun,' Henry spat out at her. 'Now, where was I? Ah yes. There I was, rootling around in Mary's bedside cabinet for a salve for my lip, and what did I find hidden at the back of her drawer? Why, it was a letter.'

Henry watched in vicious satisfaction as understanding dawned on Tom's face and he shot a nervous, questioning look at Mary. 'Ah, I see the penny has dropped. Had you forgotten about your letter, Tom? But do let me continue as the story bears telling. Now, I would say it was a love letter, but that really doesn't do it justice, does it? It's more a piece of erotica, wouldn't you say?'

'Henry, I thi-' Mary started only for Henry to interrupt her.

'And it was hidden in a Bible, can you believe? I mean, I know Tom obviously already knows you in the biblical sense but really, darling, it doesn't seem quite the done thing to put something so graphically obscene inside your Bible. I'm surprised the damn thing didn't go up in flames as soon as it touched the good book.'

'It's not what you think it is,' Mary said, trying to tamp down the panic building inside her.

'Not what I think it is? I fail to see how it could be anything else. Do you think I don't recognise Tom's writing when I see it? I've seen it often enough on business documents to know it is his hand.' Henry redirected his attention to his business partner. 'I have to say, Tom, I knew you did a stint as a journalist in Dublin, but I didn't realise you had such a way with words. You were certainly descriptive.'

Tom stared at him, defiantly.

'Do you deny writing an erotic letter to my wife?' Henry asked, his voice like flint.

'No, I don't.'

'Ah, at least you're man enough to admit it.'

'But it was all me. Mary had nothing to do with it,' Tom said, falling on his sword to save Mary. 'You were right. I do love her. But we're not having an affair. She hasn't been unfaithful to you.'

'Really? Now, do I believe that?' Henry said, tapping his finger against his lips. 'No, I don't think I do.'

'It's true. That letter is all pure imagination. Wishful thinking. Mary and I have never slept together,' Tom said firmly, looking Henry directly in the eye.

'Ah, but you see there's one problem with that. One thing that really knocks that argument flat on its arse,' Henry said, quite obviously enjoying having Tom bang to rights.

'And what's that?' Tom spat at him.

'Mary kept your letter. She didn't destroy it in disgust. She tucked it up nice and tight next to her bed. Our bed.' Henry swivelled to pin Mary with the type of look a hunter gives its prey. 'Now, why would you do that, my darling? If this is all one-sided and poor, old Tom is simply pining for you? Why would you keep the letter into which he's poured all his deep-seated sexual desire for you?'

Mary gazed calmly at her husband, her jaw set with anger, her initial panic ruthlessly squashed down and boxed up. 'Because his letter made me feel desirable. Which is more than you've made me feel for a long time.'

Henry frowned at her, displeased with that comment. 'That's not true. When I make love to you, you enjoy every minute of it.'

'Perhaps in the beginning. But now you make me feel like a slab of meat. Nothing more than a receptacle for your urges,' Mary said, witheringly. 'Even Tony Gillingham was preferable as a lover than you have been over the last few months, which is saying something. Why do you think I've been turning away from you? I have to imagine you are someone else these days to achieve a climax.'

Henry darted towards her, fury dancing across his face. Tom banged his glass down and pelted over, pushing himself in front of Mary, shoving Henry backwards.

'Don't you touch her!' he snarled.

Henry righted himself, slopping whisky from his glass, then glared contemptuously at Tom. 'You know, Tom, there's something really quite pathetic about a man pining for a woman who will never feel the same way about him. Even if she's screwing you, she will never love you.'

'You're quite wrong, Henry,' Mary said, stepping around Tom to face her husband.

Tom shot her a look. 'Mary,' he said, warningly.

'No, Tom, it doesn't matter anymore. Not now he has your letter.'

'Ah, right, so is this where you confess you are having an affair with your precious brother-in-law after all? The perfect Lady Mary is not so perfect after all, is she?' Henry jeered.

Mary looked him dead in the eye, not backing down from the confrontation. 'I'm not screwing him as you so charmingly put it. But it's not from lack of trying on my part.'

'What?' said Henry, taken aback, darting glances between Mary and Tom, noting how Tom closed his eyes briefly.

'You heard me,' Mary said, not backing down. 'I've been practically begging Tom to take me to bed. He is the one you have to thank for not making the words of his letter a reality. Because he is an honourable man. Something you know nothing about.'

'I don't believe you,' Henry sputtered, still looking back and forth between them. 'No man would write a letter like that and not sleep with the woman he wrote it about if he had the chance.'

'You cannot fathom that being the case, Henry, because you have no self-control and no morals. Tom has both in spades, much to my chagrin. He was also too loyal to you to entertain the idea of sleeping with your wife.'

'But you apparently were all too happy to set aside your loyalty to me if I am to believe your story!' Henry spat.

'You're in no position to judge. That would be rather like the pot calling the kettle black, don't you think? Except that I have not broken my marriage vows. Unlike you.'

'And you really expect me to believe this tall tale, do you? That the two of you are not sleeping together? By your own admission, you want to sleep with him, and he certainly wants to sleep with you! I've read exactly what he wants to do to you!' Henry snarled, rattled by Mary's calm frankness.

'It's the truth, whether you believe it or not. Unless you want to count me fantasising about Tom while you were labouring and grunting above me.'

Henry let out a howl at that, moving towards Mary again, only to get a powerful shove in the chest from Tom once more, sending him careening back.

'I'm warning you. Don't you dare touch her,' Tom growled, looking more like a bar brawler than a gentleman despite his black tie.

Henry scowled at him but kept his distance.

'What is it you want, Henry?' Mary asked, tired of beating around the bush. 'You obviously hope to achieve something with this letter. What is it?'

'I want us to put all of this behind us and start over,' he said, surprising Mary.

'Are you insane?' she asked him, her eyes wide with disbelief. 'You've been sleeping with another woman for over a year, and I've just told you I want to go to bed with Tom.'

'It's just a blip, Mary. We're good together, you know we are. And Caroline deserves to grow up with both her parents,' Henry said, pleading with her.

'No.'

'I'll finish it with Tabitha, I will. And it's not like you love Tom, is it? You're just sexually infatuated with him because… because… well, I really don't know why.'

Mary stared at him, pityingly. 'Oh, Henry. You still don't understand, do you?'

'Understand what?' he asked, his brow furrowed in confusion.

'I love Tom. I love him more than I can say.'

'No, no, that's… that's not true,' Henry declared, shaking his head.

Mary simply looked at him, her silence speaking volumes.

'No, I don't believe you. You love me, I know you do.'

'I don't. I realise that now. You and I, Henry, we were a mistake. We married in haste when we should have given ourselves time to realise we're not suited to each other.'

Henry stared at her in shock. 'Not suited to each other? How can you say that?'

'Does the fact that we both want other people not tell you that? You've been having an affair with this Tabitha woman for over a year. I want to be with Tom. Our marriage is over. It's dead. Now we need to bury it.'

Henry's face twisted in anger. 'I think you forget who holds the power here, Mary. I decide whether our marriage is over or not, not you.'

Mary narrowed her eyes at him, sensing Tom nudging closer to her as fury radiated from Henry. 'You cannot force me to stay married to you, Henry.'

'I can unless you want to drag your family's name through the mud. I have the proof of your indiscretion,' he said, pulling Tom's letter out of the inside pocket of his jacket. 'So, I rather think you will do as I say.'

'And what is it you think we should do?' Mary asked, wondering whether she'd be able to snatch the letter from his hand.

'Well, for a start, you can rejoin me in our bedroom tonight and we can re-establish our bond as man and wife.'

Mary's mouth dropped open at that as Tom growled beside her. 'You can't be serious? You expect me to come back to you, to sleep with you, after everything that's happened?'

'I expect you to sleep with me and then behave as a good wife should do from now on. Of course, Tom will have to leave Downton,' Henry said, tossing a dismissive glance at his business partner. 'He and Sybbie can get a residence in York or somewhere. I don't care as long as his contact with you is limited. I have no doubt that out of sight will soon equal out of mind.'

Mary gave a low laugh, startling Henry. 'Actually, it won't. We tried that and it only enflamed our desire for each other.'

Henry scowled. 'I refuse to believe you prefer him to me.'

'Oh, husband mine, right at this moment, I would prefer chopped liver to you. You will never measure up to Tom.'

Henry glared at her. 'And yet I still have the letter. So, you will do as I say.'

'Or what?'

'What?' he said, taken aback that she was not kowtowing to him.

'I asked what you intend to do if I do not acquiesce to your frankly bizarre desire to breathe life into the rotting corpse of our marriage,' Mary said, her voice still infuriatingly calm.

'Then I will make public your letter.'

'Really? And how will you do that?'

'Perhaps we could have a small reading after dinner for a start? I'm sure your father would love to know precisely where Tom wants to put his face and what he'd like to do with his tongue while he's down there. We could assess whether he's really quite as dextrous with it as he would have you believe,' Henry said, almost feeling the glow of victory warming his face. 'Or perhaps the part where he describes how he'd like you to ride him would be more suitable given your love of all things equestrian, Mary. What do you say to that?'

Mary tilted her head, looking at him contemplatively. 'I say that I would rather perform every act in that letter with Tom on the dining room table while my parents and the entire household staff look on than spend one minute alone in a bedroom with you ever again.'

Henry stared at her open-mouthed.

Tom glanced sideways at her, biting back a grin.

Mary gazed at her husband, completely solid in her determination not to give him an inch.

'I believe we are at what they call an impasse, Henry. I will not change my mind and you appear unwilling to bend. I suggest you withdraw and reconsider your strategy,' she said calmly, drawing on her years of experience in dealing with stuffed shirts and awkward characters. 'If you insist on coming to dinner, you will not breathe one word of any of this to my parents or I will put them in the full picture about your behaviour. If you feel you cannot do that, I suggest you ask Barrow to bring a tray to your room.'

Henry continued to stare at her, unable to formulate a response now she'd called his bluff and dismissed his trump card.

Mary hooked her arm through Tom's, making a move to leave the library before halting and turning back to her husband. 'Oh, and if you come to dinner, you got your fat lip in Birmingham. I'm sure you can think up an entertaining tale to cover it. It just happens to be a coincidence that Tom injured his hand at the garage today.'

With that, she turned and swept out of the room on Tom's arm.

Once they were out of earshot, Tom drew her to one side behind one of the columns in the Great Hall. 'Are you all right?'

'I think I'm better on the outside than I am on the inside,' Mary said a bit shakily as the tension began to leave her body.

Tom worried at his lip. 'You were magnificent, but he won't just take that lying down, you know. He'll regroup.'

'I know. But so will we.'

'Why didn't you burn that letter like I said, Mary?' Tom asked in a low voice.

'I couldn't. I… couldn't,' she said, looking shyly at him through her lashes.

Tom glanced around, checking the coast was clear, then leaned in to give her a swift kiss. 'I shouldn't have written the damn thing. You know he's going to use it to crucify you if you don't do what he wants.'

'That's why we're going to get it back,' Mary said, a determined gleam in her eye.