Fiz demands to know whether John's sleeping with Charlotte. Flustered by the accusation, John tries to explain that it's a case of mistaken identity and begs her to have faith in him. Not convinced, Fiz issues him with an ultimatum - he resigns from work or their marriage is over. Charlotte, meanwhile, has an ultimatum of her own - Luke's thrown her out and she needs money, so either John pays up or she'll expose his lie… As Sian's races after a distraught Sophie, Sian insists that she's got it all wrong - she was about to let Ryan down as she's the one she loves. Sian seals her claim with a kiss but Ryan's followed them and his angry reaction leaves the girls wondering what he'll do next. Will Sian be able to convince Ryan to keep quiet? Elsewhere, Dev agrees to do a job swap with Sunita for a week - he'll take care of the kids while she runs the business; and Audrey asks Lewis to move in with her.