A curiously different type of murder mystery. Hugh Sinclair is a successful crime writer who is blackmailed by a former criminal confederate, so he proceeds to bump him off. He thinks it is a perfect crime but his secretary (Dinah Sheridan) starts to try to piece the murder together - almost as a challenge - with him being her sleuthing mentor. As she gets closer to the truth, it all gets a little too close for comfort for our murderer... There is a more substantial role as the police inspector for John ("we're dooooomed") Laurie and a couple of cameos from Dora Bryan and Barry Morse, but the ending lets this down rather badly for me. Definitely better than the usual weekly Saturday feature, though, and well worth watching.