Prisoners’ Wives episode four is on BBC One Tuesday 21 February at 9pm.

Lou returns home from a night-time deal to find her flat door open and Mason’s bed empty. She panics – has he been abducted?

Then she spots him – he’s been sleepwalking. Guilt-ridden, Lou vows never to leave Mason home alone again and to become a more responsible mother. She wants to stop drug dealing. But leaving behind a world of criminality is never easy, and as Lou tries to go straight her innocent son gets himself into a lot of trouble.

Gemma is determined to see justice prevail and helps the police build a case against her husband. She goes to extraordinary lengths to protect her anonymity – but is it enough? Meanwhile, Francesca attends a prison-run marriage guidance course, under duress. Paul is hoping that they still have a future and does his best to win her back, but will Francesca capitulate?

Jonas Armstrong plays Steve, Emma Rigby plays Gemma, Polly Walker plays Francesca, Pippa Haywood plays Harriet, Natalie Gavin plays Lou.

Thanks to BBC/Tiger Aspect