Live-in nanny Helen Martin is run over by a speeding truck while trying to stop the kidnapping of her six-year-old asthmatic charge, Noah Parker. Special Agent Derek Ames of the FBI is assisting Bud on the case. He makes "a date" with Megan to check out the victim's room. A frantic call comes in from Noah. The kidnapper hangs up the phone before it can be traced. The boy's still alive. Now all the team has to do is find him.
Curtis and Ethan are able to determine that the killer/kidnapper's car belongs to a lowlife named Jason Peterson. An angry Bud tosses the guy into the interrogation room. A defiant Peterson isn't talking. Bud closes the blinds and shuts off the surveillance camera. A short time later, Jason Peterson is dead.
The initial examination suggests that Bud assaulted Peterson. Peter's been defending his detective friend, but he has his doubts. Megan finds traces of fungus that grows on wood on Peterson's body. If it comes from the place where Noah is hidden, they are looking for a place that's damp and potentially deadly for a boy with asthma.
Megan's mom, Joan, is running for re-election as a judge. She offers to help on the kidnapping case, though Megan suspects it's just a ploy to get support for her campaign. She's cynical because the pamphlet Judge Hunt is using to get votes features a photo of a young Megan after her dad died. It's a harsh reminder of the worst day of her life. Her mom looks at the picture differently. Judge Hunt sees it as a sign of strength and survival.
Bud found some of Noah's toys after he arrested Jason Peterson. Megan finds traces of blood and saliva on them. Later, a photo of Noah is emailed to his parents. He’s wearing a sign that reads "one million dollars." But what's truly troubling to Megan is the fact that Noah looks very, very sick.
An autopsy on Jason Peterson shows that he swallowed some sort of insect. He also had traces of cocaine on his teeth. Bud learns that Internal Affairs is considering voluntary manslaughter charges against him. But that doesn’t stop him from helping to narrow down the guy's possible dealers by using a list of legal cases Megan's mom provided. Ames manages to get a rundown of hiding places from the dealer, as he and Peterson used to run auto parts together. It’ll take all day to search all the locations. Unfortunately, Noah may not have that long.
Curtis says the bug the kidnapper inhaled needs open fresh water to breathe. This leads the team to believe the boy might be held at a rail yard near the Delaware River. A ditched police scanner suggests the kidnappers were there, but Megan sees that there's no wood that would account for the fungus on Peterson's body. Megan realizes that the spray pattern on a bloody tissue found on the ground means Noah has pneumonia.
Megan and Kate determine that the bruises on Peterson's neck were not lumps from Bud's interrogation. The guy died from a burst artery that came from an aneurysm that had been slowly dissecting long before he was brought into the station. That means Bud is off the hook even though he admits to Megan that he lost control in his desperation to find the boy.
The infection that led to Peterson's burst artery came from bacteria from the vaporizer filter in Noah's bedroom. That means Peterson was in his home. The team believes the kidnapping may have been an inside job staged by the boy’s dad who is dire financial trouble. But the dad is clean. The second kidnapping accomplice is actually a nanny friend that Helen trusted to watch Noah for a spell while his parents were away.
The team needs a warrant to search the home where the suspect/nanny works. Megan has no choice but to call her mom for help. She sees the entrance to a dark, damp basement around the side of the house. They find the boy. He’s sick but alive and back safely in the arms of his parents.
Megan rejects an invitation from the charming Special Agent Ames to take a celebratory ride on his motorcycle. Instead, she heads back to the office where her mom stops by to present her with an envelope. It's a newspaper clipping from the day Megan's dad killed himself. She ran away after it happened and Joan was so scared that she had lost Megan, too. It's just one more conversation that will hopefully help repair a fractured relationship between a mother and her daughter.