Ive just been looking at the BBC website as its patently clear I cant remember all of the details, and Episode 1 is still on iPlayer. Well worth watching it, it was great. But if not . (beware, some details might be missing or wrong )
At the end of the last series Harry was bundled into the boot of a car having given himself up as a hostage I forget already who to! Basically (amid much mistaken identity and red herrings!) his captors were looking for some weapons-grade uranium that only Harry (and Ruth who wasnt really dead, but living in Spain) knew the location of. It turned out that the sleazy CIA liaison guy and some smarmy British government guy were also involved, having attempted to smuggle uranium into Iraq at the start of the war to justify it Harry thwarted this operation.
Right, the baddies find Ruth in Spain and she escapes and takes flight to the UK with her partner and his son. MI5 hide them in a safe house, at this point not realising that the British government guy is a baddie, and he moves them to another safe house, where he intends to kill the man and boy if Ruth or Harry dont tell them where to find the stuff. Ruth caves in but it transpires that Harry didnt even trust her and moved it somewhere else, and he refuses to tell. So they kill Ruths partner, hence all the angsty stuff last night. Wonderful Malcolm goes to the safe house and offers himself in place of the boy. By being wonderful he makes the would-be assassin realise that killing a 10 year old would be A Bad Thing, and the man gets an attack of conscience. In the meantime Ros and DH, sorry, Lucas have found where Harry and Ruth are being kept, storm in and DH shoots the main baddie. Malcolm retires from MI5, and thats it.