Lady Dona St. Columb (Fitzgerald) is bored both with London society and her husband, Sir Harry (Fleet), so she and her children head for her family's estate on the Cornish coast. There, Dona discovers dashing French privateer, Jean Aubrey (Delon), is using a nearby cove to anchor his ship while he spies on the English. Dona and the pirate get very, very close and she decides to help him outwit the authorities. But soon Dona must choose between passion and duty.