Boston Blackie's wealthy friend, Arthur Manleder, purchases an upscale bookstore from aged Wilfred Kittredge, but retains his services as a book expert.

However, when Kittredge becomes ill just before an important auction he was to conduct, Blackie proves that he can impersonate him, fooling everyone, including Police Inspector Farraday.

That night, she and her husband, escaped safecracker Jack Higgins, break into the shop, but are forced to leave without the cash when Blackie and Arthur arrive.

He agrees to give Higgins half the proceeds, but Blackie's sidekick "the Runt" informs Gloria that he will not be bringing real cash, and that the $50,000 is stashed in Arthur's home safe.

Then Blackie forces Gloria to write out a confession, convincing her how coldblooded he can be by pretending to shoot her husband dead (the unseen Runt just knocks him out).