All hell has broken loose at Fenchurch East prison; the inmates are rioting and DCI Gene Hunt is ready to go in all guns blazing to teach the lags a lesson. However, things don't go to plan; the riot team are hugely outnumbered, and in the chaos of the retreat Sgt Viv James is left behind.
DCI Jim Keats is quick to place the blame for Viv's capture with Gene, placing further doubt in DI Alex Drake's mind about Gene's motives.
The team gain access to the prison CCTV and Alex tries to negotiate with the leader of the revolt, Jason Sachs. But her pleas fall on deaf ears, and time seems to be running out fast for Viv.
DI Ray Carling and DC Chris Skelton are tasked with bringing in a prisoner who managed to escape in all the commotion, Paul Thordy. However, during the interrogation, Alex is shocked to the core when he claims to be someone she knows - someone from her past.
Meanwhile, when Sachs asks for the press to be allowed into the prison it gives Gene the chance to send in Chris and Ray undercover; but Sachs is no fool, and soon realises they are undercover officers, leaving the pair in mortal danger.
Alex then makes a shocking discovery, and as Viv, Chris and Ray's lives hang in the balance she has to put her differences with Gene aside to try and save the lives of their team.