Devil's Platform

S1 E7: A series of mysterious deaths plague the election trail of Sen. Robert Palmer (Guest star Tom Skerritt), as does a mysterious black dog with a pentagram for a dog tag. Kolchak (Darren McGavin) 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.