Al gets a surprise visit from Sean, a boy with a transitioning parent and a troubled past. Ever-competitive Nitin can't get over Martin being Mimi's mentor. Denise's brother Dennis visits and takes a shine to Rose, much to Denise's fury. At the supermarket, Nitin bumps into Zak, the litigious snob whose wife has now left him - drunk in charge of the baby. And Ingrid is excited about her 14-year-old foster son; it's not a problem that he stubbed out his cigarette in his 'welcome' cake.
Nitin arrives early to be given a fright by Nat who has slept at the office. Denise freezes on live TV when a case of historic abuse is mentioned. Mimi and Martin's mentor/student relationship confuses everyone. Al gets a literal shock when he visits the home of vicious criminal 'Animal' Hames, and Nitin drops in on drunk parent Zak to find that booze is the tip of the substance-abuse iceberg. Rose is pelted with food before meeting up with Dennis, where she bumps into Al and Nitin on an awkward double date with a UKIP pin-up and her sister.
Rumours are flying about Denise's personal life. Nat's dislike of Mimi means she suspects her of being behind the missing files, even though they disappeared before she started. Ingrid brings her foster child Limahl into this maelstrom and Rose's car is promptly stolen. Nitin runs away from some angry Turkish men, leaving Ingrid to 'man up'. PC Harris throws the historic abuse case back in the Elm Heath court, but the files that would throw light on it are in the batch that Nat can't find. And Nat reveals that she's been hiding something under her blouse, and it's not the missing files.
It's an awkward start to the day when Rose and Dennis wake up in bed in Denise's house. Nat tries to land a birth partner with the offer of free crisps and water. Al gets lumbered with Mimi when he visits an ex-client who has been skipping classes. Rose rolls in to find Martin has dispatched Nitin to deal with her clients, a pair of drug-addicted parents, where he makes an unsettling discovery. Zak makes an unwelcome return with his wife Sophie, who is horrified when Nitin reveals the true nature of Zak's problems, with characteristic bluntness.
Rose is smitten with Dennis, but it's hard dating the boss's brother, and Lee is making a last ditch attempt to win her back. Nitin steps up to guide Nat through her pregnancy, while Martin faces insinuations about his unorthodox living arrangement with Mimi. The stray files make a surprise return, but for one member of the team it would be better if they had stayed missing. Rose gets the creeps while visiting some home-schooled children and Al decides to forsake the life of a social worker for a new start in Scotland.