Charlie Chan at Treasure Island

Sinopse

Charlie and Jimmy Chan are traveling by plane to San Francisco. Jimmy befriends insurance executive Thomas Gregory. Charlie's friend, novelist Paul Essex, dies aboard the aircraft after receiving a radiogram (message) warning him not to ignore "Zodiac". His briefcase mysteriously disappears. Charlie meets with Deputy Police Chief J.J. Kilvaine, and runs into reporter and old friend Peter Lewis. Charlie also meets noted local magician Fred Rhadini, and discusses Essex's death with the three men. Rhadini tells Charlie about Dr. Zodiac, a psychic preying on the rich in San Francisco. Charlie, Rhadini, and Lewis go to Dr. Zodiac's home, where Dr. Zodiac conducts an eerie séance. Lewis' fiancée, Eve Cairo, has been meeting with Dr. Zodiac, angering Lewis. Later, Kilvaine reveals that Essex was poisoned, but can't rule out suicide. Jimmy spends the afternoon following Thomas Gregory, whom he believes stole Essex's briefcase when leaving the plane. He discovers Essex's manuscript in Gregory's hotel room.