Spade goes to his lawyer office to ask him what Iva had told him. After some badgering, Spade eventually gets Sid to tell him that Iva confessed to not being at home the night that Miles was killed.
Flashback to the night of the murder: Iva had been trying to get a divorce from Miles, and that night, he had come home to say he had a date with a girl at the St. Mark. Thinking she might have a chance to use this information as grounds for divorce, Iva followed Miles to St. Mark. She saw him come out of the hotel, but he wasn't on a date. He was shadowing a man and a girl, the same girl she saw Spade with yesterday (a.k.a. Brigid, of course).
To kill time, Iva drove downtown and saw a movie. She went to Spade's apartment twice, once at 9:30pm and a second time at 2am, but Spade wasn't home. By the time Iva came home, Miles still had not returned, but shortly after that, Effie came by with the news of his death.
After Sid is done recounting Iva's story, Spade is unsure whether or not to believe it, but admits that all the details fit the timeline, at least.
Spade returns to his office to find a worried Effie, who tells him that Brigid never arrived at her apartment.
Spade's able to track down the taxi driver who picked up Brigid, and he tells Spade that Brigid asked to stop for a newspaper (the Call) and then said to take her to the Ferry Building.
After Spade buys a copy of the Call, but can't find anything in the paper that seems relevant to Brigid or the black bird. He takes a taxi back to the Coronet, but finds nothing in Brigid's hotel room except an empty jewelry box.
Returning to his office, Spade then comes face-to-face with the boy working for Gutman, who wants to meet with Spade. They drive to the Alexandria, and as they're walking down the corridor to suite 12-C, Spade punches the boy and manages to wrestle both pistols out of the boy's coat pockets.