Comic artist, just released from an insane asylum, kills those he feel ruined his life. Entertaining enough comedy-horror. First you need to know it stars Barry Bostwick and Karen Black, which tells you part of the story, and then that it stars Kevin Corrigan, which tips the film into the hoped-for one of the two places it could go given that first fact. Kevin Corrigan, who, yes, you do know who he is, has pretty much only ever been in watchable movies, near as I can tell.
