The new prisoner intake at HM Prison Shadwell includes one Danny Simpson, a.k.a. DC Danny Glaze, undercover to ascertain the whereabouts of £11 million stolen by fellow prisoner Andy Burton. Glaze manages to hold up against the prison guards and a gang led by Rufus Anderson, as he works to gain Burton's trust. He convinces his cellmate Ricky Sefton to smuggle some crack into the prison, and then to plant it in the cell of Burton's right-hand- man, FA. With FA out of the picture, Glaze helps Burton out until he trusts him enough to take him along in a daring escape. Unfortunately for Burton, his operation and the escape plan have been taken over by Paul Grint, an old associate turned enemy, and he and Danny are held prisoner in a disused office building. DCs Lennox and Riley interview Rufus Anderson, who tells them he recognised Glaze as a cop, and told Andy Burton who he really was. By following Burton's friend, Dave Markham, whom Burton suspects has sold him out to Grint, CID work ...