Beware Young Stranger — Ellery Queen

When a diplomat's daughter falls in love with a man suspected of murder, he goes in search of the truth in this classic from the legendary mystery author.

The kids call it spring break, but their parents know it by its true name: debauchery. Every Easter, hormone-crazed students pile into cars and drive thousands of miles to the beach to lose themselves in an orgy of beer, sand, and sex. Keith Rollins and Cheryl Pemberton are two such revelers: college sweethearts planning to marry the moment they graduate. But in the heat of a party, the couple gets separated; the next morning, the girl is found raped and murdered beneath the pier and Rollins is the prime suspect.
 
Though Rollins is never convicted of the crime, the cloud of suspicion lingers over him. Years later, he becomes engaged to the daughter of diplomat John Vallancourt, who resolves to find out the truth. When Vallancourt's daughter disappears, he fears the killer has struck again.