It's the second last show of the entire series, and we find Inspector Thomas Lynley turning to booze to cope with the death of his wife, Helen. He has to pull out of it soon enough, though.
"Limbo" actually begins 12 years earlier, when Lynley's young godson goes missing during a party and is never seen again. Shift to the present, and the boy's skeleton is found in a drain that has been covered with bricks. The family asks Lynley to go to Italy and see if he can encourage the boy's sister to return. Lynley ends up having sex with her, and the next morning, he is arrested for her murder when she's found dead on the pavement below.
DC Michelle Tate (Geraldine Summerville) is looking only at Lynley for the murder, doubly suspicious of him because he's a detective. So it falls to him and to Havers to solve the murder - fast.
This is a pretty good episode with plenty of suspects and intrigue. There are a couple of plot holes, but thanks to the actors, it still works. Geraldine Summerville is very good as a no-nonsense DC who thinks Lynley looks good for the murder. Nathaniel Parker and Sharon Small are wonderful as she tries to goad him out of his misery.
Recommended.