Mystery! Episodes on PBS

As this “Touching Evil” drama concludes, Creegan and Taylor (Robson Green and Nicola Walker) are hot on the trail of the person who's torching people to death. The first breakthrough: the killer's motive. Fire, Creegan surmises, is “a magical element which turns him from victim to victor.” It turns out that he's almost completely on the mark. Simmons: Andrew Scarborough. Van Der Tewst: Andrew Powell. Lynn Southy: Alison Newman. Dutronc: Alain Bourgouin.