A couple of thugs have a bank robbery planned. Rufus is the henchman, and the professor has the plan organized to the minute. Their crime isn’t even noticed until the next day when the bank opens and the open safe is found along with the murdered guard. The precise professor seems to have far reaching accomplices. Though Inspector Farraday is baffled with his clues, Blackie sees the story as obvious. They onlyarrive at the same conclusion when the accomplice from the construction site is found ded.

The bickering Blackie and Farraday hash out the details as they decide where to go from here. The hysterical wife of the dead construction worker has calmed down enough to phone Farraday with the tip about the professor. Meanwhile, the professor and Rufus are planning another robbery, complete with another construction site and patsy to help with their diversion. Farraday is at least on the ball enough to stop the robbery, but his killers get away.

Elsewhere in the city, the hysterical wife from earlier in the story goes to Blackie with her information, and a tip on where the professor lives. Blackie is a bit more subtle when he sneaks up on the professor, but can he take down the crook? There’s still one element in the story, and one that the professor never counted on. Don’t mess with a mama bear.

The hysterical widow has her own ideas of revenge and justice, but before anything can go wron, Blackie has recovered from his knock on the head and made sure things won’t go wrong this time.