Blueprint for a Caper

A man who works for an insurance company is killed when a guy attacks him and throws him down an elevator. The police think it's an accident but the man's wife doesn't think so, so she hires Barnaby to investigate. What they don't is that the man was providing a group of thieves with info on various clients so they can rob them. And the man who killed him is the leader who just got out of prison. It seems that the man was getting together with the leader's girl who's also a member of the gang. And there's dissension in the gang when the leader insists on restoring the...