Retired friends Charlie (Walter Matthau) and Herb (Jack Lemmon) pose as dance instructors on a cruise ship in this comedy. The underhanded Charlie coaxes his recently widowed brother-in-law to join him on board without disclosing the two will need to dance. Instead Charlie promises there will be plenty of available and lonely women at sea. Once on the ship, Charlie's promise proves accurate, and he starts romancing the wealthy Liz (Dyan Cannon), while Herb falls for Vivian (Gloria DeHaven).