Honolulu is experiencing 100-plus-degree temperatures. Tani and Junior get called in to help out HPD with a rash of crimes. A woman, Tracy Benson, kills two cops and a passing motorcyclist. Dog cancels his golf game with Grover, but Grover stubbornly decides to play anyway. Jerry discovers Benson died in 2015, so the woman is hiding out in Hawaii under a false identity. The man holds teens who are using his pool without permission at gunpoint, and Junior talks him down. Then a man steals Tani's car. She blames Junior for leaving the key in the cupholder. Grover is having the round of his life. Jerry arrests a man who tries to steal ice, and he explains it's for his pregnant wife. Kamekona decides to overcharge with his shaved-ice monopoly. A print Danny found identifies "Benson" as Alison Ross. She escaped during a prison transfer with a half-million in cash. That cash was later stolen by the air-conditioning repairman. Junior tells Tani his sister was killed by a drunk driver. Then they get ice cream. Grover sinks a 30-foot putt to shoot par, then discovers his caddy has passed out and didn't witness it. McGarrett and Danny find the repairman, but Ross has escaped with the money. McGarrett figures out Ross is trapped in the elevator with the power out. She's dead from the heat. Jerry retrieves the man's pregnant wife and puts her in the cooler at the convenience store. Kamekona's customers rioted against his price gouge. Grover brags to the others about his round, and Gary testifies for him. The man stole Tani's car for the AC, and she arrests him for it. The thief drained the car's battery by leaving the AC on the whole time, and it dies. So they jump into the ocean.  It starts to rain, cooling everyone down.