The second time it happens is completely different.

All three of them are coming down off the high of a successful vote, and Jo is flushed and happy and fully in command of herself. They can't go to the pub to celebrate now that she's not drinking, so they go for a walk instead and she buys ice creams for him and Kirsty, as if they're kids. He imagines that she probably does the same thing for her little boy when she has her time with him at the weekends, but it seems best not to dwell on that too much.

As this is running through his head, Jo, who has been rummaging for something in her handbag, looks up and catches him watching her, and he grins a bit guiltily.

"Want my Flake?"

He pulls it out of the ice cream and offers it like a prize, and she takes it, then smiles up at him and says thanks. Her eyes are bright with the simple pleasure of being out of the office on a rare sunny afternoon, and it's nearly enough to make his heart explode. He wishes all their days could be like this, but at the same time he knows both he and she need the intense, challenging times that come with the job, too. It would be dull if things were always easy.

With Jo occupied by chocolate, he looks round for Kirsty and finds her half turned away, eating her ice cream as fast as she can. Kirsty doesn't like to share, which is something Danny has come to accept; after months of struggle, he's learnt that the way to be friends with Kirsty is to take her as she is and not expect her to change. When he shared this insight with Jo, she laughed and said he was growing up at last. He's still not certain whether he should be pleased or annoyed by that.

They stroll and chat for another quarter-hour, and then Jo says that she's going home early for once, and they both should as well. Danny looks at Kirsty—just because Jo can't go for a drink doesn't mean the two of them can't—but Kirsty says she's going to see if they can fit her in at the hairdressers. Split ends, she says, tossing her mane of perfect waves over her shoulders in a gesture that makes Jo roll her eyes behind Kirsty's back. The three of them go their separate ways, and he thinks that will be it until tomorrow. It'll do him good to have an evening in. Maybe he'll even read something that's not for work.

Once he's at home, though, he can't seem to settle, going from book to book and never getting through more than a page or two, and he's not sorry at all when his mobile rings and it's Jo with a question about some documents he compiled for her. He starts to talk her through them on the phone, but then looks at the spill of abandoned books, thinks how bored he'll be if he's left alone with them, and asks if he can just come round and show her in person.

He's out the door, jacket in hand, almost before she's finished saying yes.

These days, Iain lives in the house that he and Jo used to share, with the baby and the Macedonian (or was it Moldavian?) nanny, who is soon to be the new Mrs Porter, and Jo has a flat that she hasn't bothered to decorate because she only uses it to sleep and shower. Danny has visited it twice before, and both times found it a muddle of cardboard boxes with the tape still on, lamps sitting on the floor, and pictures leaning propped against the walls, waiting to be hung up properly. Jo says she'll wait until the summer, when things are quieter, and sort it all out in one go, but he'll believe that when he sees it.

When he's almost there, he realises he hasn't eaten since the ice cream and is starving. Jo is unlikely to have anything but the biscuits and milk and fish fingers she buys for her son's visits, and he doesn't want to be fed a toddler's dinner, so he detours to a Thai restaurant in the next road over and gets an enormous takeaway that makes her laugh when she opens the door.

"Christ, Danny, did you leave anything there for other people to eat?"

"Not my problem," he says, grinning. "Can I come in?"

It's a little better in the flat than the last time—the boxes have all been unpacked and cleared away, at any rate—but it still feels cold and unfinished, and as if no one really lives there, which he supposes is not too far from the truth. They sit at Jo's glass-topped table and eat tom kha kai and yellow curry and fried rice with crab while they go over the documents, and at last Jo puts down her pencil and says it's enough for one evening.

"You sure? I can keep going..."

Jo shakes her head. "I've decided to take advantage of the times when I don't have to keep working all night. It makes up for all the times when I do." She folds up the top of the Thai container closest to her, tucking in the flaps and smoothing them down precisely, as if it's important to get it just right. "You don't have to go yet, though, if you don't want to. We could watch the news. Or talk. In fact, I think we should talk."

"Why? Am I being sacked?"

He's only joking, but Jo looks shocked.

"No! Of course not. It's just that we never did after that night, the one when—"

"I'm pretty sure I know the one you mean," Danny says. He wasn't expecting this and feels wrong-footed, worried that he's finally going to catch it after all these months. It's not that he's forgotten what happened between them—it would be difficult to forget—but he's tried hard to put it out of his daily thoughts and carry on as usual, and he thinks he's been mostly successful.

"Yes. That one." Jo's gaze is level and steady, but there's a faint blush of colour high on her cheekbones. "I know it's been ages and I should have said something before, but, well—you know how much else was going on at the time."

"You don't have to say anything now," he says. He can hear a pleading note in his voice and hates himself for it, but can't seem to stop. "It wasn't your fault. You were drunk."

"I've used being drunk as an excuse for a lot of things in the past, Danny, but not for this one. I wasn't so drunk I didn't know what I was doing. I knew you were sorry for me—almost as sorry as I was for myself—and I took advantage of that to get you to do what I wanted. I shouldn't have done it and I apologise. I just—I wanted to feel as if someone cared about me."

"I did care about you. I do."

"I know," Jo says, very softly. She glances down at her discarded pencil and rolls it back and forth on the tabletop with one finger. Her left hand still looks bare without her wedding ring, and he wonders if it feels strange to her. He knows she doesn't love Iain anymore, after all the betrayals, but they had been married for ten years and it must have been familiar, if nothing else. How could anyone blame her for feeling cast adrift?

"I have an idea," he says.

"What?"

"Suppose we have another go at it—no one pissed, no one guilty, everyone fully consenting."

Jo's face looks like a master painter's rendition of disbelief. "Really, Danny? I've just finished apologising to you for making you have sex with me, and you're inviting me to do it again? What sort of fucking idea is that?"

"A serious one," Danny says. "We can't take the first time back, but we can have a time that you don't feel bad about. Sort of like a reset. Make sense?"

"No," Jo says, "it doesn't make sense at all."

"But would you like to?"

She stares at him, as if she's searching his face for some sort of deception or mockery, and he thinks he might be about to get sacked after all, or at least chucked out of her flat, but then slowly, incredibly, she nods.

"Only if you really mean it, Danny."

"I really, really mean it."

"Oh," she says, and suddenly she smiles—not the practised smile that she gives to constituents and television presenters, but the soft, lovely one that he only sees once in a blue moon. "Well, then...I suppose I would."

She takes him to her bedroom, which he hasn't seen on either of his previous visits, and which is tiny and cream-painted and mostly filled by a double bed. The duvet is pale blue with daisies, which seems like an oddly girly choice for Jo, but perhaps it was a gift from someone. Inside the open wardrobe are clothes that he recognises from seeing her wear them to work: a grey ribbed jumper, a bright green silk blouse, a black skirt. Her dressing gown is hanging from a hook on the back of the bedroom door, and this small detail seems almost overwhelmingly intimate. He's not sure how he can have seen her naked, touched her everywhere, been inside her, and still feel shaken by the sight of a dressing gown, but he does.

"Danny?" Jo puts a hand on his arm. "Are you okay? It's all right if you've changed your mind."

"I haven't. Of course I haven't."

He's hesitant to make the first move, even though this was his idea, and it's a relief when Jo helps him out by pulling his face down to hers and kissing him. She's as good at it as he remembers, maybe even better because she's sober now, and he stops worrying and just lets things happen.

It's not complicated at all this time. Everything is very simple, and he loves it, and her.

Their clothes are all over the floor and Jo's on top of him, looking down with that intent expression she gets when she's concentrating hard on something. Her dark hair is slipping out of its tidy French twist (he knows it's a French twist because of Kirsty, who once spent a slow afternoon at work looking up the instructions for doing one) and he reaches up and tries to tuck the stray pieces back into place, which makes her laugh a bit breathlessly. She catches hold of his hand and presses it to her lips.

"What would I do without you, Danny?"

"You'd be fine."

"Would I?"

"You know you would." He touches her cheek, not quite caressing. "But you'll never have to find out."

Jo leans in to kiss him again, and he wraps his arms round her and thinks this has turned out to be an excellent idea after all.