Coach Hayden is practicing with Julie Teeger's basketball game. The coach talks about how the team should play hard no matter who is coaching them. After practice Julie asks her what she meant and the coach passes off her comment. After the girls leave, Hayden starts to take a shower but hears a noise. Dismissing it, she continues with her shower as a figure plugs in a hair dryer and leaves it outside the shower, then loosens a pipe and plugs a drain with a towel to form a puddle of water. When Hayden comes out of the shower, she steps in the puddle and is electrocuted.
Monk is ironing his shoelaces when Julie and her two friends Emily arrive to hire him. The two Emilys are upset because their towel and hair dryer were involved in the death, which the police consider an accident. Rather than face the girls' tears, Monk agrees to take the case, but Natalie shows up and suggests Monk should refuse, but she figures it'll give the girls closure. However, he insists on going through with the investigation.
At the school, Monk can't help but admire the trophies, since he never won any. They check out the showers and Monk notices the outlet plate was put on upside down and discovers a loose wire. Noticing an open window, Monk sends Natalie up to discover footprints.
Monk and Natalie check out Disher's evidence and Monk notices that the tape on the hair dryer is jagged, and there's a burr in Hayden's shoe. Natalie talks to Stottlemeyer about Julie interviewing him for a school report on DNA. Stottlemeyer is busy with a number of cases, including a two-week-old fire in a nearby valley, and refuses until the next week. Natalie responds by offering to set up a meeting with Joe Montana and Stottlemeyer immediately accepts, proving he's free after all and forcing him to do the interview with Julie.
Monk and Natalie visit Principal Franklin to get a list of people with access to the locker room. Franklin mentions that she had seen Hayden crying in the teacher's lounge the day before her death, and is worried that the basketball team will have to forfeit. Natalie volunteers to fill in for their next game and Franklin agrees. Monk ends up having to volunteer to become her assistant.
At the gym, Natalie and Monk arrive to coach the team (and in Monk's case, adjust the net). Monk perks up when he hears everyone on the team gets a trophy. Afterward, Monk lets them know it wasn't an accident and notices one of the girls has an arrowhead necklace from the same valley where the fire occurred.
Monk and Natalie check out the valley and the park ranger reports that someone was camping, the wind shifted, and the fire spread from there. Monk is a bit more obsessed with coaching (and his new whistle) than the fire, but focuses and notices the same burrs that were in Hayden's shoe. Following where someone would have ran away from the fire, he finds a button from Hayden's coat that places her at the scene. However, he can't figure what the motive would be if the fire was an accident.
They go to talk to Hayden's brother, Aaron, and reveal that they talked to Hayden's friend. The friend had explained that Hayden was going to turn herself in, and Aaron tried to persuade her not to. Monk admires Aaron's country club trophy and complains about the cracked frame on the photo of Hayden, the one that Aaron is donating to the school. At the police station, Julie conducts her DNA interview with Stottlemeyer and Disher (Disher doesn't know much), and they discuss a murder victim, Paula McGoohan, from a case two years old. There was DNA at the crime scene, but no one could connect it to.
Aaron is watching the news and hears that they're declaring the fire the result of foul play. He goes to the cabinet and burns Paula McGoohan's driver's license.
Monk is busy clearing his mantle in preparation for a trophy, then goes to the game where they have a brief moment of silence for Coach Hayden, a moment ruined only by Monk's efforts to clean a scuff mark off the floor. Stottlemeyer and Disher are in the stands watching. Once the game begins, Monk's whistle-blowing drives the referee to distraction and he's forced to take Monk's whistle.
When Natalie protests a call, the referee throws her out and Monk is forced to take her place and they're down by 4. They start to make a comeback, and in the locker room Natalie notices a picture of Coach Hayden, with the same cracked frame they noted at Aaron's apartment. She dresses up as the mascot and brings the frame to Monk to show him that the frame was repaired with the same tape that was on the hair dryer. Aaron is at the game and notices them with the frame.
Natalie goes to Stottlemeyer while Monk calls for a timeout to present his theory. With the clock ticking down, Monk explains that if Hayden had turned herself in, they would have run a routine DNA check and her brother Aaron would have matched the DNA found at the McGoohan crime scene. When the time out is over, Aaron makes a run for it and Disher and Stottlemeyer capture him. Julie puts the team ahead by a point with two seconds left. Monk is disheartened and sure enough, the opposing team makes another shot to win the game. Monk loses again.
Later at Monk's apartment, Natalie and Julie give him boxes full of trophies – one for every case he's solved, rounded down to 100.