Berserk (1967)

Starring Joan Crawford, Ty Hardin, Diana Dors, Michael Gough, Judy Geeson

Directed by Jim O'Connolly
(actor & director credits courtesy IMDB.com)

A series of murders at a traveling circus cast suspicion on the ruthless circus owner, who's been trying to find a way to revive the outfit's sagging box office.

One of a number of horror films fashioned as star vehicles for Crawford in the 1960s, this one wisely balances the sinister goings-on with genuinely entertaining circus performances, including an elephant act, acrobats, and even an assortment of trained poodles, making the climactic high wire act seem even more realistic and suspenseful.  However, Crawford's a bit too old to be presented as she is as a convincing object of desire for the male leads, and when the killer is finally revealed, there's a great deal of gaping plot holes that are never filled in.  Nonetheless, it's still an enjoyable picture.