And the Sea Will Tell (1991)

A rich couple, James Brolin and Deidre Hall, die aboard their yacht near the remote South American island of Palmyra. Suspicion falls on a free-spirited duo, Hart Bochner and Rachel Ward, who’d become their friends. It seems obvious the hippies had a hand in it—but the real mystery is whether the man acted alone while the woman watched helplessly, or if she was a willing partner in the crime.