It's a good episode, with the usual twists and turns that make WAT special. A father desperate to prove his son innocent of the crime he's been convicted of suddenly goes missing for no apparent reason. Is he so despondent that he's suicidal? Has he been killed by someone in the victims' family? As usual, the truth is discovered by a kind of circuitous route and it's kind of sad all round, since everyone and no-one is at fault. It also raises the issues of the death sentence and whether innocent people are being executed, and some of the characters reveal their views on it.
The ending is frustrating but completely right for the episode. There's no neat winding up of the story, and it's left up to us to decide what might have happened.