At the Daily Planet, Jimmy surprises Chloe while Senator Burke pays a visit to the city. The surprise: The Big Sleep, with Humphrey Bogart. They're interrupted by a gunshot and run out into the main room to see a man fleeing up the stairs. Jimmy takes a picture of him as he gets away, and then they find Lana in the elevator with a gunshot wound.
Clark arrives as Lana is taken away by the EMTs and Jimmy snap photos. Lionel is apologizing to the unconscious Lana and vowing to find whoever is responsible. Lex arrives and wants to know why they left the opera, then suspects his father was involved. Lois is trying to check out the crime scene and manages to sneak out a cigarette case. Clark feels guilty and Chloe suggest he check things out, while Jimmy works on the photo he took. He goes over the photos while The Big Sleep runs in the background, then someone knocks him out.
Jimmy wakes up to hallucinate himself working at the Daily Planet newsroom… in the 1940s, with the paper owned by Lex Luthor. Chloe works for him and Clark is a klutzy reporter who has just started working there. None of them know the "real" Jimmy, who gets a call from a woman asking him to investigate a murder: hers.
Jimmy meets with the woman in the alley and discovers it's Lana, who claims her husband Lex is trying to kill her. Jimmy agrees to help her and she shows him a cigarette case with matches for a club called the Talon. Jimmy goes there and spots Clark, who is a regular, and wants to know what Jimmy is checking out. Lionel runs the club and Lois is a lounge singer. Lex comes in to talk to his father and note he's no longer controlling the town like he once did.
Lionel slips Jimmy a tip on Lex on who he slips out of the club and switches cars. Jimmy follows Lex to a barn (Clark's in real life) where he meets with Lois who he's having an affair with. He plans to dispose of his wife Lana, and Jimmy snaps a picture then drives off into the night. Lex follows but Jimmy manages to get past a speeding locomotive and Lex goes off the road.
Jimmy goes to the Luthor manor to meet Lana and give her the photo of Lex and Lois. Jimmy plans to take care of Lex and she gives him a gun as they kiss. He meets with Lex and tries to blackmail him with the photo. Lex claims he plans to divorce Lana, not kill her, then reaches beneath his jacket. Jimmy shoots him but it turns out Lex was reaching for his cigarette case. He says the word "Gardenia" before dying, and Jimmy runs off. The police put out an APB and Chloe gets involved.
Jimmy goes back to the Talon where Lionel dispenses advice. Chloe tracks him down and reveals that Clark Kent has been receiving calls from Lana. As they leave, Lionel calls Lana and reveals that Jimmy is on his way. Clark is with her and she assures him they won't have to sneak around much longer as she leaves… with a gun in her purse.
At the Daily Planet, Jimmy arrives to confront Clark only to find Lana waiting for him with a gun. She shoots Jimmy, but it hits him in the cigarette case he has in his pocket. Clark arrives and shoots her, then reveals he's an undercover cop sent to watch Lex and fell in love with Lana. The police arrive to take Jimmy into custody… and he wakes back up. Chloe's there and Jimmy's attacker took the photo of him. Jimmy spots the cigarette case with a gardenia on it and realizes Lana was there to see someone else and the cigarette case is now gone, and it held something important. They go to the elevator and check the memory, and realize she was meeting a reporter, Brennan. They go to his office and confront him, but he denies everything. Brennan admits he was meeting with Lana who said she had a story for him, and panicked. Before he can explain, someone shoots through the door and Jimmy goes after the man. Chloe calls Clark while Jimmy tackles the man in the hallway. Chloe tries to help and gets knocked down and over the stairwell railing. Clark shows up just in time to rescue her while Jimmy knocks out the killer, and Clark slips away before Jimmy can spot him.
Later Lionel is waiting for Lois at her apartment. He knows she has the cigarette case and wants it back. The cigarette case belonged to his wife Lillian and it contains a flash drive. It contains a file of Lex meeting with Senator Burke about Project Ares, something Lionel was unaware of. Lionel warns her then leaves with the flash drive.
The next day Chloe confronts Lana at the hospital and she admits Lionel was forcing her to spy on Lex. Lana is concerned about Clark now that she knows he has a weakness. She asks Chloe to keep her secret.
Later Clark meets with Chloe and reveals he can't find the killer. He realizes Chloe is holding something back but she won't tell him, and she warns him that he might not understand what's going on. They both realize that Lex wouldn't hurt Lana so there's only one other person.
Lex gets word that the attacker was captured by the police then killed in custody, and that it was his gun on the crime scene. Lana was carrying it to protect herself and the killer used it against her.
Jimmy meets with Chloe and tells her that he's leaving on assignment thanks to the publicity from the news story on him breaking the case. He takes a picture of his kissing her before leaving.