Captain Joe Martin arrives at the British colony in Aden, with his new wife Honor, to replace the popular Captain Nick Page of the Royal Military Police.

As dawn draws near, Sergeant Baxter and Corporal Dimarco work with the SAS on Operation Starfish, a top-secret mission to capture Abdul-Kadir Hakim.

Captain Joe Martin demands that American journalist Martha Franklin hand over incriminating evidence; Christmas festivities at the Royal Military Police base are interrupted by a surprising development.

Tilbrook takes Markham to visit a key prisoner; the RMP begin a desperate search; Alison, struggling with her pregnancy, confides in Honor about her affair; Ed gains intelligence that promises danger.

Alison keeps watch over Ed, despite her conflicted feelings towards her marriage. The NLF desire a trade, Yusra sends Armstrong a coded message, and Joe defies orders.

Joe's future in the army is uncertain. Armstrong worries about Yusra's safety. Honor is crushed with the revelations of Joe's secret past. Markham struggles to choose between duty and his own morals.