This text details a mystery featuring The Three Investigators, a young detective trio who are hired to solve a complex riddle left by the deceased Marcus "Dingo" Towne. The boys must decipher cryptic Cockney rhyming slang clues to locate a hidden fortune in gemstones before it is stolen by greedy rivals. Throughout the investigation, they face interference from the Percival relatives, a malicious peer named Skinny Norris, and dangerous hired thugs. Jupiter Jones, the group's leader, ultimately deduces that the family lawyer, Roger Callow, is a traitor attempting to steal the inheritance to pay off gambling debts. Following a high-stakes pursuit aboard an ocean liner, the detectives successfully recover the jewels and ensure the fortune reaches its rightful heirs.