December 12, 1929. This night, gangster Arnie Kurtz is in a car, watching a hit he ordered. Another car, speeding along and with a chopper blasting, guns down a pedestrian; but the victim pulls a gun and fires back, his bullet goes through the windshield. The car crashes; the driver is dead, but the hit-man escapes. Arnie Kurtz goes to establish his alibi; at 10:35, his wife Stella drops in on her brother Benno Fisk, who owns a pawn shop. Stella has a job for him: deliver a payment of 100 Gs to a gangster in Washington, DC, for her hubby Arnie. Benno will be gone for 3-4 days, so Stella takes his 2 pet birds with her; Stella and Arnie are permanent guests at the swanky Lakeview Hotel. A newspaper headline reads: "Parrot Fever Kills 2 More."
Ness and his men investigate the shooting of the pedestrian; Rico finds the driver's license of the dead driver of the getaway car: he was a New York hood named McHuey. It seems the New York Syndicate figures into Arnie Kurtz's trying to take over the Southside of Chicago. December 13, Benno Fisk arrives in Washington, but he's feverish and collapses on the street; he just manages to hide his case with the 100 Gs. At 12:20 p.m, 2 doctors are on the case: Dr. Victor Garr, about 50, with a lot of experience and a deep care for patients, and Dr. Daniel Gifford, about 30, inexperienced and has a habit of always doing things by the book. When Benno, almost delirious, manages to say a few words..."Stella Kurtz...Chicago"...Dr. Gifford takes a 3:45 plane to Chicago. Meanwhile, a girl and a boy find the case with Benno's 100 grand.
In Chicago, Rossman and Youngfellow have Arnie Kurtz's phone line tapped; they listen in on a call, a gangster waiting in Washington did not get his 100 grand. Arnie says he'll go to Washington to replace it. Arnie and Stella argue, he accuses Stella's brother of running off with the dough; they fight, he slaps her, she leaves taking the birds with her. At 9:16 p.m. in the hotel lobby, Dr. Gifford arrives, and is intercepted by Rico who is keeping tabs on Arnie. Over Rico protestations, Dr. Gifford goes up to Arnie's room, intending to quarantine him, even though Rico said any interference would ruin their stake-out. Sure enough, Arnie bolts down the fire escape. Rico phones Ness, and a few minutes later Ness and Dr. Gifford have a discussion about which is more important: quarantining infected people or tracking criminals.
Next day Dr. Gifford, since he's in Chicago now, visits other "parrot fever" patients in the Cooke County hospital. Ness and his men take a train to Washington, but stubborn Dr. Garr won't let Ness see his patient Benno Fisk. Back in Chicago, Dr. Gifford talks to an infected clarinet player and an infected gentleman--they have something in common, they had both been to Benno's pawn shop recently. Dr. Gifford takes a fast taxi over to the pawn shop; he finds Stella Kurtz dead, and the infected birds.
Back in Washington, the girl and boy turned the case with 100 Gs over to Officer Cavanaugh--when he talks to Dr. Garr, the doc finally agrees to let Ness see his patient. Benno says he was supposed to leave the dough in a bus station locker, and pick up a bag. By posting warnings about "parrot fever," Ness gets a tip on Arnie Kurtz, staying at the Maybrook Hotel under an alias. Arnie Kurtz goes to the Lincoln Memorial to pay a gangster 100 grand, in exchange for a bag containing names, addresses, info on breweries and distilleries, and contacts...everything Arnie will need to take over the Southside of Chicago. But Ness and his men show up, and arrest both Arnie Kurtz and the gangster, thus foiling another plot to expand the rackets in Chicago.