A psychopath tries to forcibly persuade a tennis star to agree to his theory that two strangers can get away with murder by submitting to his plan to kill the other's most-hated person.
 
Alfred Hitchcock is no Stranger to suspense.
 
Hitchcock's Signature Cameo:  Alfred Hitchcock appears (at around 10 mins) The man boarding a train carrying a double bass as Guy disembarks.
 
FUN FACT:  In the scene where Ruth Roman and Patricia Hitchcock are watching the tennis match, Ruth gives Patricia a real U.S. ten dollar bill. Showing real U.S. money in movies then was illegal without permission from the U.S. Treasury Department. The Treasury Department later removed the prohibition for Psycho (1960) and later movies.