Maddie and Buck reunite, while Chimney and Hen reunite as well. It's revealed that Maddie and Chimney have broken up.
A man goes out on a chartered boat to go down into a cage underwater with professional divers. While underwater, he sees a shark and freaks out, disarming the boat's cage and then floating up to the surface too rapidly.
The 118 is called as the man is suffering from decompression sickness. With little time to wait for transport, the team turns a nearby fish freezer into a compression chamber to stabilize him.
Eddie goes to therapy with Frank, and Frank tasks him with reaching out to some of the people who understand his first trauma.
Taylor officially moves in with Buck. Later, Maddie stops by with Jee-Yun, and he admits to her that asking Taylor to move in was a dumb decision, perhaps spurred on by his fear of being left.
Chimney has lunch at the station and worries about Maddie spending her first day alone with Jee-Yun in months.
A pet sitter is tasked with caring for tarantulas for a week. One night, some of them get loose and climb into bed with him. Having not heard from the sitter in a few days, the owner calls 911 for a wellness check. The police find the sitter in bed covered in webs. Jonah and Hen are able to get him stabilized.
Buck admits to Taylor that he kissed someone, though he fails to mention it was Lucy. He then admits he asked her to move in shortly after that, and Taylor rightfully gets upset and leaves the loft.
A robber holds up a woman, Pauline, at a gas station. She taunts him and then douses them both with gasoline and hits him with the pump before fleeing. Later, Athena identifies her and talks to her sister, who tells Athena that Pauline has been different lately with mood swings, irritability, and voice changes.
Dispatch gets calls about a woman standing on the roof of a recycling plant, and it's revealed to be Pauline. After speaking with Athena, Hen figures out that Pauline is suffering from a disease that has hardened the part of her brain where fear is produced. Pauline still attempts to jump after speaking with Hen, but Buck and Ravi are able to get to her first.
After failing to bathe Jee-Yun the day before she was in her care, Maddie soaks her daughter in the tub where the incident took place months earlier.
Taylor returns to the loft and questions whether Buck intended to trap her, and Buck is unsure, but they both decide they want the relationship to work.
Eddie calls one of the people he served with, who was in the helicopter with him when it went down. Later, Christopher hears what sounds like items falling and cannot get into Eddie's room, so he calls Buck.
Buck arrives and breaks into Eddie's bedroom, where he finds Eddie's bedroom smashed and Eddie crying.
Eddie tells Buck that everyone he saved from the helicopter is now dead, and he's afraid he will never feel normal again.