Kolchak: The Night Stalker - Season 1 Episode 7 -

A series of mysterious deaths plague the election trail of Sen. Robert Palmer, as does a mysterious black dog with a pentagram for a dog tag. Carl investigates and finds that the Senator has made a pact with Satan in return for the ability to assume the form of an indestructible black mastiff, and destroy his enemies both within his own party and opposing him. Kolchak must confront Palmer and destroy the pentagram before Palmer kills him.