Episode 1 of DTF St. Louis commences in 2018 as Clark Forest, a celebrated weatherman in St. Louis, pedals off to work on his recumbent bike. Simultaneously, Floyd Smernitch, an American Sign language interpreter, endeavors to forge a bond with his stepson, Richard, though he frequently interrupts his prepared speech to complain about his protruding belly during a group therapy session.
Later, Clark works alongside Floyd as his sign language interpreter during the broadcast of an extreme weather event. Floyd is present, and he saves him from a flying stop sign. The men bond at the convenience store later as Clark thanks him for the save, and Floyd opens up about his Peyronie’s disease. Two weeks after they started working together, their friendship blossoms swiftly. They start working out together, and their families interact during Floyd’s cornhole party. Six weeks later, the party shifts to Clark’s house, and Floyd brings the cornhole boards, noting that Clark and Carol, Floyd’s wife, did not play the game much last time.
During this party, Floyd observes Clark relocating the swings, insisting that it is to ensure his daughters’ safety. In reality, he is moving the swings to get a better view of his female neighbor during her yoga sessions. Floyd assists him with the relocation, and they later sit side by side on the swings when Clark introduces him to an app called DTF (Down To Fuck) St. Louis. It is an app utilized by married individuals to spice up their marriages by secretly meeting with other married people for sex without commitment.
Clark makes a persuasive case for the app, which intrigues Floyd, and he opens up about his marital troubles. It emerges that Floyd’s wife, Carol, has taken up a side hustle as an umpire. The boxy padded uniform she wears during the games turns him off. Meanwhile, Carol complains to Clark’s wife, Eimy, about his obsession with comic books and how he is so dull that he can barely follow the plot of a book. Similarly, Clark’s sex life is also in shambles. His wife works late at night doing charity work, while he wakes up early for work.
Returning to the DTF St. Louis app, Clark invites Floyd to meet at the steakhouse later in the day so they can explore the app together. Floyd initially declines, but after a relatively dull evening spent with Carol and Richard, he relents and calls Clark. As they wait for their orders, Clark helps Floyd set up a semi-truthful profile on the app. All Floyd has to do now is wait for someone to like their profile and arrange a DTF meeting.
Eight weeks later, Floyd is found dead. His body is discovered in a secluded location, accompanied by a can of Bloody Mary and a picture of a nude Indiana Jones with his face scratched off. Detective Homer from the St. Louis County Sheriff's Department and Plumb from the local suburban cops arrive at the scene to investigate. Initially, they clash over jurisdiction and perspectives, but eventually start working together.
Homer initially dismisses the case as simple: Floyd went to a secluded place to view pornographic material and died of a heart attack. Plumb, however, suspects there's more to it, so she continues her private investigation. She examines security camera footage from businesses in the area and discovers a recumbent bike pedaling through the area and parking at the same secluded pool house where Floyd was found the night of his death.
Plumb presents her findings to Homer, who authorizes her to start an official investigation. While he investigates Floyd's communications, she looks into recumbent bike sales in the area. She discovers that only two such bikes have been sold by the local bike shop in recent years, both to Clark.
Homer lures Clark to the station for questioning before handing him an official search warrant for his phone. Clark insists that he was not at the pool house on the day of Floyd's death. After examining his phone records, Homer discovers an affair between Carol and Clark that spanned three months. Carol tried to end it and return to a normal life with her husband, but Clark was unwilling to let her go.
With the affair, the recumbent bike sale, the CCTV footage, and the autopsy results indicating that Floyd died of poisoning, Homer has enough evidence to arrest Clark during one of his weather broadcasts. The news report on his arrest describes his crime as a crime of passion.
At the end of the episode, Homer talks to Clark at the station, and he reveals that the events began during a cornhole party at Floyd's house. In an ASL conversation earlier, untranslated, it is revealed that Floyd signed to Clark, who was learning sign language from him, that "I know you're fucking my wife."
