Jazz saxophonist and arranger Ray Sherwood, touring with the Jack Donovan Orchestra, is haunted by personal tragedy. But when a beautiful and talented Berkeley student named Gail Prentice seeks his help in orchestrating a highly original composition called Swing Around the Sun, which is slated to premiere at the Golden Gate Exposition on the newly created Treasure Island in San Francisco Bay, Ray finds himself powerfully drawn to the beguiling coed. Within moments of first setting eyes on her, Ray also witnesses a horrifying sight: a young woman plunging to her death from the island's emblematic Tower of the Sun.