A young Irish immigrant gets a job as a conductor on a streetcar and fights off an attempt by crooks to take over the company, all the while pursuing the boss' beautiful daughter.

When multi-millionaire banker John Argyle is found brutally murdered in his home, suspicions are cast upon Mary Mazuret, his adopted daughter who became the sole beneficiary of his estate under his will, Argyle having quarrelled with his son Bruce. Just as the case begins to look black for Mary, Asche Kayton, a great private detective, is called in by Bruce and takes hold of the investigation.