Night watchman Harry was killed and the safe blown, a crime committed with precision by "The Professor" who plans everything with exacting purpose, and his stooge Rufus. No one heard the bank blast because a blast went off at the same time at the construction site. But that was no mistake, it was also planned by The Professor. Then when the construction worker blackmailed The Professor for more money for his part, the construction worker ends up murdered too. Inspector Faraday and Boston Blackie now have two unsolved murders and a bank robbery to solve.