Blackmail leads to murder on a yacht and a cash-filled purse on the bottom of the ocean weighted down with a gun. Paul Drake investigates by driving a speedboat surrounded by bikini-clad beauties who take turns water skiing. A wealthy man comes to Perry Mason to obtain his help to protect his stepdaughter from being blackmailed about a secret from his past. But as with any good mystery nothing is as it seems and the stepdaughter is protecting not her father, but the family of the young man she intends to wed. From there the twists begin, which unravel in the courts.