The team at Section D is in mourning following the tragic death of Ros Myers, who was killed in an explosion while trying to save the British Home Secretary, as the award-winning spy drama returns for its ninth series. Section Chief Harry Pearce is hit particularly hard by the loss and he's dismayed to learn that a trusted friend has blood on their hands. Harry wants revenge and will stop at nothing to get it.

One month later, Lucas North boards a ship in Tangier to track rising Somalian Al Qaeda star, Abib. Alongside Lucas is Special Boat Service (SBS) agent Dimitri Levendes, who is masquerading as the ship's captain. An unexpected interruption from what appears to be Somali pirates puts Lucas in mortal danger. His unlikely saviour is an Eastern European prostitute, who he later discovers is undercover mercenary Beth Bailey, also sent to track Abib.

The pirates are a much bigger threat than first anticipated – they are in fact an Al Qaeda cell who have smuggled explosives onboard and are headed for the UK.

After escaping the ship and returning to London, Lucas and the rest of Section D concentrate on stopping the floating bomb. Beth, who is keen for a job on the Grid, turns up unexpectedly with information about the boat. Harry remembers Beth from the past and is unsure whether she can be trusted but, with time running out, the team has no other option. Harry is forced into taking drastic action to prevent a terrorist attack that could hit Britain at its very heart – the Houses of Parliament.

Meanwhile, Lucas is shocked when he is visited by an unwelcome ghost from his past.

Harry Pearce is played by Peter Firth, Lucas North by Richard Armitage, Abib by Peter Bankole, Dimitri Levendes by Max Brown and Beth Bailey by Sophia Myles.

"Head of Section D"!