The Woman on the Beach (1946)

Coast Guard officer Scott (Robert Ryan) loves his fiancée, Eve (Nan Leslie), but he can't fight his attraction to the alluring Peggy (Joan Bennett), a lonely beauty he meets on the beach. But Peggy is trapped in a loveless marriage to Tod (Charles Bickford), a former painter whose career was cut short by blindness. Scott and Peggy become romantically involved, yet they can't help but feel that Tod knows more than he's letting on -- and his blindness may just be a ruse he uses to spy on Peggy.