A tense thriller that tears the lid off Soho's underworld and reveals the cunning organisation behind a gang of safebreakers who will stop at nothing, not even murder, to achieve their goals. The mysterious Mr. G is boss of a gang undertaking daring safe robberies. Jimmy Baxter (Wayne Morris) of Anglo American Investigations is on his trail. Also on the trail is feeble Inspector Felby (Lloyd Lamble) who "wants this lot badly" after the theft of Lady Wilshaw's diamond tiara ends in murder. The showdown is at a pawnbrokers where the crooks send the police a hail of bullets.