Dressed to Kill -Sherlock Holmes -1946

Three cheap musical boxes (each one playing a subtly different version of "The Swagman"), manufactured in Dartmoor Prison, are sold at a local auction house. However, a criminal gang is determined to steal and recover all three, even if it means committing murder. Sherlock Holmes tries to recover the music boxes and crack the secret code contained in the tune before the gang can get what they want.