Lord Sinclair (Roger Moore) and billionaire playboy Danny Wilde (Tony Curtis) are friendly rivals who happen to solve crimes together, usually under the watchful guidance of a Judge Fulton (Laurence Naismith). Whilst on holiday in Monte Carlo, the body of a young girl is discovered in the sea. Sinclair and Wilde trace the dead girl's final steps, stumbling across millionaire businessman Koestler (John Phillips), his wife Lisa (Melissa Stribling), and high strung executive assistant Crane (Terence Alexander). The trail leads to a plot to smuggle stolen gold, disguised as counterfeit coins, out of Europe.