The city is in the midst of a heat wave. Andy hasn't seen much of Luke lately, as he's been busy trying to solve every homicide under the sweltering sun. She has, however, been riding shotgun with Sam for seven straight shifts and doing all his paperwork. Dov says, "You're like his hot secretary with a gun." He meant "hot" in the good-looking sense, not the other "hot" even though Andy's that, too.
Crazy things happen when the temperature rises, as Andy and Sam discover while in hot pursuit of a Mr. Delightful ice cream truck. The driver was asleep in the back when a young girl stole the vehicle. They bring the girl back to the station along with many boxes of ice cream sandwiches. You know, as evidence.
The heat is getting to Chris, who is sleep-deprived thanks to some party-hearty neighbors. He almost rips the head off a guy who stole air conditioners from a Seniors Center. Traci learns that he is disillusioned by all the self-serving knuckleheads living in the city. He doesn't want to become one of those people. Traci assures him that's not gonna happen. And when his noisy neighbor voluntary decorates Chris's front porch, he realizes that not everyone in the city is selfish. Nice.
Dov and Gail hear screams from the apartment of a pregnant woman. She's in terrible pain but won't go to the hospital because she's agoraphobic. The heat wave has the city's EMT's working in overdrive. So when the woman's water breaks, Dov and Gail realize they've just been invited to an impromptu birthday party. The rookies work well under pressure and deliver a healthy baby boy. Mom is extremely grateful. She agrees to go to the hospital but steadfastly refuses to name her new son after Dov. Bummer.
Sam hurt his hand during the ice cream truck takedown, so a pretty doctor who happens to be at the station offers to stitch him up. Her name is Monica and she's someone Sam's been casually seeing. There's tension in the humid air when Monica meets Andy, who is then sent off with Shaw to check out the park where the young girl who stole the truck was playing.
Andy and Shaw respond to a call from a woman whose daughter is missing. She was playing in the same park where they were headed. Andy calls Sam at the station to talk to the ice cream truck thief. She has a hunch that maybe the girl didn't take the truck for a joyride. Andy thinks that maybe she was trying to use it as a means to escape from something, or someone. Sam says he'll check it out just as a citywide power failure hits. Ice cream truck girl had sticky black markings on her feet and Shaw notices a tar-filled area in front of a closed building. Andy scopes out the top level of the building while Shaw runs into a building worker on the lower level. He asks the employee to unlock a door to the basement, as some faint tapping can be heard on the other side. The worker smashes Shaw over the head with a flashlight. He grabs Shaw's gun and takes aim.
Andy is on the phone with Sam when she hears the shots. She's rushes to find Oliver hurt, but alive. Gotta love Kevlar. Shaw knows that the shooter is off to kill the missing girl. Andy has no choice but to go after him alone. She makes her way through the darkened halls, flashlight on, gun drawn.