Marco Page (Harry Kurnitz) adapted his own novel about a rare book dealer who finds stolen books and solves a complicated murder case.
Rare books dealer Joel Sloane (Melvyn Douglas) kisses his secretary, who is also his wife Garda Sloane (Florence Rice). Insurance detective Steve Langner (Minor Watson) gives Joel $3,000 for recovering stolen books. Ned Morgan (Shepperd Strudwick) accuses Otto Bruckler (George Zucco) of framing him for stealing books and tells Leah Bruckler (Mary Howard) he can't get a job. Eli Bannerman (Louis Calhern) asks Otto for $5,000 for stolen books. Eli gets doctored books from Sidney Wheeler (Dwight Frye). Joel and Garda learn that Otto was murdered, and Ned is suspected. Garda tells Joel that Otto's secretary Julia Thorne (Claire Dodd) has expensive clothes. At Otto's office Joel chats with Lt. Flanner (Donald Douglas) and Steve. Julia introduces Joel to Eli.
Eli socks Sidney, who pulls a gun and takes Eli's money. Joel has lunch with Julia and asks her to be his partner in finding books. Garda comes in and shows Joel a threatening note. Ned tells Joel that he did not kill Otto but saw him dead. Joel tells Garda he is going out for books but drinks with Julia at her apartment. Julia tells him of Otto's secret compartment. Joel learns that Ned was arrested. Ned's lawyer Arnold Stamper (Douglass Dumbrille) gets Ned to admit that Joel gave him money. Joel is questioned by District Attorney MacMillen (Thurston Hall) but refuses to betray Julia. Stamper calls on Joel, who suspects that Otto was a fence for stolen books. Eli finds Sidney in a bar and has him shoot Joel. Eli takes Sidney out in the country and shoots him dead. At the office Julia tells Eli that Joel is alive, and she refuses to give Eli a letter. Eli offers Danny (Horace McMahon) $1,000 to kill Joel. Joel and Julia find that her apartment was searched. Eli has a gun, and Julia asks Joel to leave. Eli took the letter and her money, but she asks him to take her away. Joel asks Lt. Flanner to arrest Eli.
Lt. Flanner calls on Joel to say that Eli had $5,000. Paul Terison (Nat Pendleton) with a gun joins Joel in a taxi. MacMillen has to release Eli. Danny asks Eli for $2,000 more to kill Joel. Paul keeps Joel tied up. Garda follows the car of Danny and Eli. Joel gets free and knocks out Paul. At the house Eli and Danny grab Garda and Joel. Garda kicks the lights out, and the police come in. Garda goes home, but Joel goes to Julia looking for Eli. Julia gives Joel a list of stolen books and says that Sidney killed Otto. Joel explains why Julia killed Otto, and Julia throws a knife at him. Eli comes in with a gun; but Joel overcomes him, and Flanner catches Julia. In the final scene Garda puts handcuffs on Joel and kisses him.
Witty banter between Joel and Garda lightens this detective story that makes a hero out of a rare books dealer.