Beau Nash is a "gentleman crook" who headquarters his gang of jewel thieves in a run-down boardinghouse. When one of his gang, Mike, gets arrested, his sister Claire--aka "Lady Byron"--swears to get revenge. The gang frames Donald, the best friend of the detective who arrested Mike, for a jewelry store robbery. The detective gives Donald--and his new love, Claire--a short time to find the thieves and clear his name before he takes him in.