Peter catches sight of a house engulfed in flames. He rushes inside to find a semiconscious woman lying on the floor. She reaches for a stuffed turtle and shouts "dad" as Peter carries her out of the inferno. BOOM! An explosion rocks the neighborhood. Thankfully, Peter and the woman make it to safety.
The woman Peter saved, Jenna Applebee, is in critical condition. The arson investigators, Ray Easton (guest star Tony Serpico) and his young colleague, Skip (guest star Aaron Tveit) won't let Megan take the body until they complete their investigation. The theory is that the dead man is Jenna's estranged husband, Mike. But Megan determines through dental records that whoever she has on her table is definitely not Mike Applebee.
Megan realizes their John Doe suffered a fractured hand and took a blow to the head before dying from carbon monoxide poisoning. She heads over to the fire scene to look for the murder weapon. Ray Easton is still investigating. He likes to be thorough so that he can fire Geraldine, which is the name of a toy cannon he ignites whenever he closes a case. Once again, Megan is made to wait. This guy, Ray, really is playing with fire now!
The team identifies their John Doe as Ben Dupree. He worked with his mom, Louisa Armstrong, at an organization called Families Reconnected. They reunite adopted children with their birth parents. Jenna Applebee was a client. The injury to Ben's hand came when Jenna's birth father, Daniel Robinson, closed a door on it after a visit that did not go well.
The police arrest Mike Applebee, who swears he would never hurt Jenna. Ray Easton also believes this guy is the killer based on his investigation. Peter believes they should be looking at Daniel Robinson. He reveals that Jenna called out "dad" when he rescued her. This case has become very personal for Peter, who lets Megan know that he was adopted. He tossed away an envelope that had info on his birth parents a long time ago.
Daniel Robinson says Jenna came to see him the night of the fire. Curtis tries to retrace Jenna's last steps. He finds traces of floor cleaner from the donut shop where she worked on her shoe, as well as a pebble from the front of Robinson's home. Jenna also stepped in paint after leaving her birth dad's place. This is all vital info in what has just become a murder investigation, as Peter informs Megan that Jenna Applebee is dead.
Jenna received a blow to the head just like Ben Dupree. The fire released toxins that left traces of cyanide in her system. Jenna was recovering from that initial poisoning which means her death occurred from cyanide that was administered to her while she was in the hospital. But who had access?
Skip the arson guy treats Peter to some donuts from Jenna's shop as they scan hospital security footage. Daniel Robinson's daughter was on the premises, but the girl only wanted to console Jenna for what her dad had done. Later, Peter informs Daniel Robinson that Jenna kept the stuffed turtle he got for her all those years ago before he gave her away. Told ya this case was personal for him.
Sam and Megan come across a toy store that suffered a small fire. Ray Easton had mentioned that one of his open cases is an arsonist torching toy stores. Megan believes the arson investigator may be the fire-starter after they find a toy canon fuse at the store. Bud doesn't believe Ray, who comes from a long line of cops, is a killer. He changes his tune when they realize the blunt force trauma wound came from a leather-covered sap, which is weapon cops hand down to their kids.
Ray informs Megan that he never had a son, so he handed his sap down to Skip, who was seen by Jenna as he was trying to set a toy store fire. They knew each other from the donut shop, so Jenna trusted this fireman when he offered her a ride home.
Megan realizes her partner is in danger, as he went to check out the toy store with Skip, who gets the drop on Peter with his gun. Fortunately, the cavalry arrives to take the guy down. But it'll take Ray Easton some time to get over the fact that his partner/protégé was setting fires right under his nose.
As Kate's relationship with Megan's ex moves forward, chats are as icy as ever between them. Things seem to take a turn for the better after Kate showed her support for Megan during the case. As for Peter, he pays a visit to Louisa Armstrong. He informs her that they caught her Ben's killer. He would also like to know if Louisa would help him find his birth parents. She says nothing would have made her son happier.