The episode begins with the Boyle Family's morning routine. Everything is normal until Cousin Becca discovers Pappy Boyle dead.
Jake and Terry accompany Charles to the Boyle Family Farm.
Rosa brings Holt his lunch. Amy asks Holt about his marriage counseling; both Amy and Rosa give Holt romantic advice.
Cousin Sam greets Charles when Charles, Jake, and Terry arrive at the Boyles. Sam tells Charles about Pappy's missing will, and Jake thinks Lyndon, Pappy's son, killed him.
Amy checks in on Rosa and Holt. She scolds Rosa for her idea to get Holt to date again, but Rosa explains her real motive. Amy agrees.
Charles reviews his eulogy with his cousins. Jake brings them all to the barn, where he announces someone had poisoned Pappy.
Charles, Jake, Terry, and Sam meet on the front porch and discuss Lyndon as a suspect. They call him in to interrogate him. Afterward, Charles, Jake, and Terry question the other Boyles to corroborate Lyndon's story.
Rosa takes pictures of Holt for his dating profile. Amy gives Holt advice for the right pose.
Jake calls Lyndon back, and Lyndon explains the truth. Charles, Sam, and Lyndon introduce the Boyle Family Jar to Jake and Terry. Jake finds a hair on an opened rat poison box. Sam suggests that all the Boyles should provide a strand of hair so that Lyndon is not alone.
Rosa and Amy help Holt navigate his dating app.
Terry receives the DNA results -- the hair was from a rodent. Jake reads the results and realizes that Charles isn't related to the Boyles. Jake calls Charles's dad, who admits that Charles's mom had an affair. Jake and Terry agree not to tell Charles and prove Lyndon is the murderer another way.
Amy and Rosa meet Holt at Shaw's Bar, where Holt is meeting his date. Amy and Rosa watch Holt and his date.
Charles, Jake, and Terry secretly follow Lyndon to prove he is the killer. Jake discovers who is responsible for Pappy Boyle's death.
Amy and Rosa attempt to stop Holt from leaving with his date, but Holt confronts the girls and tells them he knew what they were up to the entire time.
The next day, Charles is ready to leave, explaining he delegated eulogy duties to Sam. Jake realizes Sam set up Charles to learn he was not a real Boyle. Sam confesses, but Charles is still upset about not being a Boyle.
Amy and Rosa apologize to Holt. Holt confides in them about his feelings regarding his marriage counseling with Kevin. Amy and Rosa insist Holt should tell Kevin how he feels. Kevin arrives at the precinct in the pouring rain. They both admit they still love each other and kiss in the rain.
Jake apologizes to Charles as they are about to leave. Then, Jake insists that Charles try to open the Family Jar to prove he is a true Boyle. They gather the cousins, and Charles pries it open. He celebrates with his cousins as Jake and Terry recoil from its terrible smell.