Ten-year-old Millie Harris moved in with the Linfield's at the Crafton, Maine, a lighthouse in 1952. Millie's stay was temporary while her parents delivered a yacht to the Bahamas. Her half-sister, an FBI agent, told Millie her parents were kidnapped. A second yacht, nearly identical to the first, was to be sent with CIA agents to investigate. Millie wanted to help, but she couldn't do it alone. She recruited Rocky Linfield to help, and they stowed away on the yacht. After arriving in the Bahamas, they received help from Pinky, a native Bahamian, who had helped the US Navy during World War II by watching for Nazi submarines. Suffering attacks with a grenade, flares, a scouting knife, and Rocky's slingshot, the kidnappers were rounded up.