Question: What was the name of the 1975 American thriller film directed by and starring Clint Eastwood, co-starring American actor Jack Cassidy?
Sentence (from "The Eiger Sanction (film)"): Based on the 1972 novel "The Eiger Sanction" by Trevanian, the film is about an art history professor, mountain climber and former assassin once employed by a secret United States government agency who is blackmailed into returning to his deadly profession and do one more "sanction", a euphemism for killing.
Relevant evidence: No