September 8, 1934. A cruise ship from Cuba to New Jersey has caught fire. There are over 300 passengers on board and some of the passengers and crew are jumping overboard to avoid the flames. Ness and his men, on assignment in New Jersey, speed to get there when the ship docks, Ness having an arrest warrant for Valentine Ferrar, racketeer and founder of the Big Syndicate. Valentine Ferrar had been in Cuba, picking up a million bucks collection money for the Syndicate. Ness is told by a ship's official that Ferrar has drowned but the eyewitness was not reliable, it was his sidekick Inky Beggs, who has just left for New York. Actually, Inky is being taken for a ride by two hoods to deliver him to The Underground Court in Manhattan. Inky tells his story to the cocaine snorting Judge Foley and the other members of the court. He tells them truthfully that Ferrar jumped into the water with a million bucks in his money belt but he lies about Ferrar drowning.
Judge Foley lets Inky go, but has him tailed. Inky leads two of Foley's hoods, "Bo" Narins and Pedro Palmas, straight to the Grandview Auto Court where Ferrar is hiding. Ferrar shoots Pedro, and Inky for betraying him. Then Ferrar tells Narins to deliver Ferrar's resignation to the Syndicate. Within half an hour, the manager has reported the shootings and the 2 dead bodies to the police, and Eliot Ness and his men are investigating. They find out Ferrar answered a personal ad in the newspaper: "Man wanted. Share driving chores with lady. Destination: San Antonio. Telephone: BAyside 0-8879."
Valentine Ferrar, using the alias Mr. Williams, goes to her house and meets Hannah "Lucy" Wagnahl; she is an eccentric, wealthy widow. Her husband, Gordon, died 5 years ago, and every year on September 9th, she makes a trip to San Antonio (she says). It is like a 2nd honeymoon, though Platonic, and this is her 5th trip. She calls Ferrar "Gordon." But Ferrar goes along with it, he wants to get halfway across the country, and by travelling with a lady he would be inconspicuous. Little does he know that Ness and his men are already on their trail. After midnight, on a lonely stretch of road, a carload of hoods sent by the Syndicate starts firing at Ness' car, with Hobson and Youngfellow in the back; Youngfellow gets winged in the right shoulder. In the shootout, Ness and Hobson shoot three hoods, and capture the one with the chopper: "Bo" Narins. Back at police headquarters, Ness gives Narins the 3rd degree; Narins protests he'll have Ness "impeached."
But Narins tells him that Ferrar has a letter addressed to Eliot Ness, to be delivered in the event of his death. It names names, and gives information about the Syndicate and their Underground Court. The Syndicate is more worried about that letter than the million bucks Ferrar embezzled. The police phone a description of Lucy Wagnahl and Ferrar to all gas stations along the way. Ferrar is surprised to find out she took his letter while he was asleep, and tore it up; however, she memorized it first. Lucy and Ferrar don't go all the way to San Antonio, they stop at a cottage she owns in West Virginia.
The following day Lucy gets stopped by Ness but Ferrar is not with her. She says he caught another ride at the crossroads; Ness rides with her back to New York. In Ness' New York office, Lucy gives her statement but Ness notices some inconsistencies. They decide to let her go home, and keep her house under surveillance for days knowing that the syndicate will likely get in contact with her. One night, some Syndicate hoods go to her home and take her to the Underground Court. Ness and his men follow the car. Ness, Hobson, Enrico, Jack Rossman and Youngfellow have a shootout with the Syndicate. Judge Foley shoots Lucy, critically wounding her; Ness shoots Foley. At the hospital, the dying Lucy tries to recite the letter to Ness. Lucy tells him the letter said, "To Eliot Ness. If you read this, I'll be dead..." But then she dies herself. Later, at the Honeymoon Haven cottage, the police dig up the backyard and discover the bodies of 5 "Gordons." Ferrar had been poisoned with arsenic by Mrs. Wagnahl and buried in her backyard at the cottage but with $1-million still in his money-belt strapped around his waist, he was the richest "Gordon" in Lucy's garden.