Maddie prepares to get married as the guests wait anxiously outside the venue. She wonders about someone’s whereabouts, and Hen tells her that Buck’s care just pulled in.

Buck and Eddie arrive disheveled, and Maddie wonders where Chimney is, to which Buck says, “It’s complicated.”

Flashbacks reveal Buck at Chimney’s bachelor party, welcoming in guests Eddie, Tommy, Hen, Karen, and Ravi. After Chimney fails to show up, everyone leaves except Buck and Eddie.

A group of people accidentally enters their karaoke room, and Buck asks them to stay. Buck and Eddie then party at the karaoke room with the strangers before taking the party to Chimney’s hotel room.

After breaking into the room, Buck and Eddie continue to party overnight. Upon waking up the following day, they realize Chimney was never in the hotel room.

At the wedding venue, Maddie calls Chimney’s phone, which he doesn’t answer. She searches for him on ‘Find My Friends’ and discovers his phone is on a street in LA.

Chimney awakens in his car on the side of the road to a man tapping on his window. The man asks him various questions, and Chimney appears disoriented. When the man offers to drive Chimney to where he’s headed, Chimney gets out to get in the passenger seat, and the man steals his vehicle and throws his phone into the street.

Four days earlier, Chimney has dinner with the Lees as they gather to have a meal on the anniversary of Kevin’s death. He tells them he has been jittery and has had a headache for several days. He also laments Buck trying to throw him a bachelor party.

In the present, Chimney walks out into traffic to get his phone and is almost hit by a bus. He then gets on the bus without retrieving his phone, which is run over.

A cop finds Chimney’s broken phone and calls Athena, who is gathered with everyone at the venue. Maddie questions if there are cameras nearby, which the officer confirms.

Maddie, Hen, and Josh head to the dispatch center, where they pull up the cameras and see Chimney get on the bus.

Chimney wanders the streets until he arrives at a bakery.

Maddie and Hen watch the footage from inside the bus, showing Chimney talking to himself. Sue and Josh tell them the bus driver said he talked about being late for work.

At the bakery, Chimney talks to a worker there, believing the establishment to be the karaoke bar he worked at years ago. Chimney has flashbacks to his time at the bar and then sees a bloodied Doug, which causes him to flee.

Athena and Bobby go to the bakery, while Athena calls Maddie and tells her what the worker told her.

Maddie, Hen, Sue, and Josh wonder if Chimney knows what year it is, and Hen remembers a call from two weeks prior.

At the call, Chimney went into a ventilation duct inside a hotel to help a man who was stuck inside after peeping on two people in a room. Once Chimney gets to the man, he helps stabilize him while the 118 works to cut through the vent and get them down. The man explains he was spying on his fiancée, who was in the room with another man.

Once out of the building, Hen and Chimney talk to the man’s fiancée, who tells him he’s not telling the truth, as they’ve been divorced for several months.

Buck and Eddie come to dispatch to visit Maddie, and the Hen informs them, after calling the hospital, that the peeper from the call two weeks ago had viral encephalitis and died that morning. With Chimney being near him previously and showing symptoms, they believe he has it.

Chimney ambles around Los Angeles and comes upon an outdoor market when a car crashes into several people and stands. Chimney starts to triage the scene but leaves abruptly after helping someone when he sees Doug again.

Bobby, Athena, Buck, and Eddie arrive at the scene of the market and begin canvassing the area on foot.

Chimney hears Buck on the street calling for him, but he’s unwell and hidden behind a covered patio. Doug appears again, mocking him, and he struggles on his hands and knees to get away.

Chimney begins to have flashes of Maddie before Kevin appears to him and urges him to go home.

Chimney breaks into the Lees house, asking them where Kevin is. They tell him Kevin is dead, and he promptly passes out.

Chimney wakes up in the hospital with Maddie in the room and apologizes for missing the wedding. He tells her he is always fighting to return to her and Jee-Yun. He then asks her to get married that day.

Everyone gathers in Chimney’s hospital room, where Chimney and Maddie get married.

Tommy comes late, in full gear from a fire, and he and Buck kiss. The soot on Buck’s face tips his team off to their relationship.

Sometime later, Maddie and Chimney snuggle in his hospital bed and catch up.