The scene opens with Jane trying to cajole Joe Friday into doing his business. But then she gets fed up and tells him to stay out there all day for all she cares. As she leaves to go inside, FBI Agent Gabriel Dean strolls up with a bouquet of flowers in hand. Agent Dean gives Jane the flowers and she gives him a nice big friendship hug. She asks him what he is doing there. He requested a transfer to D.C., which is still a bit of a commute to Boston. And then he leaves. Over at Casa Isles, Mamma Rizzoli and Mother Isles walk in on Maura attempting to make a perfect cup of espresso. She gets flustered when her mother walks up and lets out an adorable “dammit.” Mother Isles is apparently staying with Maura.
Jane and Maura walk to the factory crime scene together ostensibly taking about Agent Dean but really doing a status check on their own relationship. Jane says “Dean asked me to dinner.” Maura says “So go,” but a little too quickly and defensively. Maura asks whether Casey and Dean know each other. And then Maura says Dean only left for Afghanistan because Jane wouldn’t read the Sunday paper in bed with him. Maura says Jane can’t even call Dean by his first name, Gabriel. Everyone else is Frost, Korsak, Dean. Jane calls Gabriel’s name “weird” and “biblical.” And she certainly doesn’t want to get biblical with any Gabriel. The firefighters bring out their fallen comrade. Frost and Korsak start talking about the case. The jeans factory fire appears to have been started by a faulty space heater. They then bicker, about whether the skeezy owner of the factory is “old” and who filled up the tank last and then Jane asks if they need a moment alone to they can “fight.”
Back in the autopsy room, Jane says she never understood guys who want to run into burning buildings. Maura looks at her hero girlfriend and says, “You chase murderers.” Jane says back, “Not if they’re on fire.” She asks if Jane knows why firefighters call their outfits “bunker gear.” But when Jane knows that one already so a disappointed Maura moves on to an even more obscure fact about who first invented the helmet. And with that one she succeeds, much to her not-so-secret satisfaction, at getting Jane to ask her if her brain ever gets tired with all the “useless information” she stores in there. Maura tells her no, her brain never gets tired. Jane wonders why the firefighter’s mask and gloves are scorched, but the rest of him is unharmed. Maura calculates that the heat that scorched the firefighter is higher than the heat generated by the factory fire. Maura tells Jane she wrote an article on just this in the Journal of Combustible Science.
Jane agrees and says it was a “fabulous article” and the “loved the photos.” Maura helpfully offers to print the article for her and Jane tenderly stops her “Maura, why waste paper, I’ll read it online.” Janey was exercising her other favorite trait: sarcasm. Maura recognizes this and says, “You’re not going to read it. “ And then she gives her a little look again. Maura then says she knows Jane is going to dinner with Gabriel. Jane asks how she knew. To which Maura replies, “You brushed your teeth.” Maura suggests she double date with Jane and Dean, since she already has reservations for dinner with her mother. Jane replies: “Oh – you, me, Gabriel and your mother? How can I say no?” Jane says if it was anyone but Maura it would be “the creepiest idea ever.” Jane asks if it was indeed arson and Maura replies: “No. Yes. No” While talking about arson, Maura’s eye wanders.
She says she thinks Gabriel is a good match for Jane. Jane says, “Nobody asked you, yenta.” Later that night Maura leaves her single date with her mom all smiles. Mother Isles is being sweet and all, “I wish we’d done this more. I wish that I’d stopped being busy and just enjoyed you.” A car out of nowhere is revving at them. Mother Isles pushes Maura out of the way and gets hit, rolling onto the windshield and then back onto the street. Back at Jane’s she is prepping for her hot “date” with Dean. He says he wants her all to himself, to which Jane says he can take her out because she won’t run away with the busboy. Maura calls Jane and informs her about what just happened. Jane runs to the hospital immediately. Frost is already working the hit-and-run reenactment, and Maura tells Jane to “go and do what you do better than anyone I know – find the bastard who did this.” So she does, and Frankie is there too. The hit-and-run accident wasn’t an accident at all, he was gunning for Maura.
And just then Maura’s biological dad, Paddy Doyle, shows up in the hospital. He says he came to check on Maura and Mother Isles because she is a good woman. Maura is unimpressed says she’d rather not be reminded that he fathered her. She says she’ll give him to the count of three to leave before she screams. In desperation, he says he’ll tell her who her mother is and Maura replies that she doesn’t like to be toyed with. Jane arrives and they talk about Doyle and whether Maura wants to know who her biological mother really is. Jane says they’ll catch him and Maura says she’s not sure she wants them to. Jane says she doesn’t know if everything will be OK, but that she is here for her. The team is working both cases – the possible arson and the hit-a-Maura. Jane tells Frost and Korsak that Doyle is back in town, but she didn’t notify authorities.
Still, she knows they’ll have to take him down at some point. Frost asks how Maura will feel about that and Jane says, “After all this, I hope relieved.” Gabriel shows up at Jane’s house that night with a six-pack of beer. He says he came back for one reason. Which was to drink the six-pack with Jane. In the next scene Jane is shown waking up and slapping Gabriel’s hand off her face with an annoyed look. And then she says, “Oh crap, I’ve got to go check on Maura.” he asks Jane what he can do for her, she says, “Yeah, you can go away.” Back at the police cafeteria, Mama Rizzoli is giving Maura some special mom-in-law TLC. She says she won’t leave until she finishes her pancakes. Jane shows up and the Rizzoli women look at Maura together with worry. Jane tells Maura she told Gabby about Doyle being back in town, but he promised not to do anything until she said he could.
Maura thanks her. The team tracks down the perp’s car, and Maura gets overwhelmed at the scene when she seems her mother’s blood on its bumper. When Maura gets back to the hospital Doyle is there. He shows her pictures of herself he carries with him in his wallet, and said he always wanted to be the kind of man who could be her father, but is just a low-class thug from South Boston instead. He tells her a little about her birth mom, who had Maura when she was 18 and was brilliant and beautiful. Then Mother Isles wakes up and says she thought she heard “Patrick” in the room. Maura is back in the office working to distract herself because if she doesn’t she’ll cry. Jane hands her a washer they found in the car that hit her mom. It is the same washer that is missing from the space heater that caused the factory fire. The cases are related. Maura then finds some more interesting evidence about the substances found on the fallen firefighters mask and the hit-a-Maura driver’s floor mats.
She gathers Jane, Frost and Korsak to demonstrate. Jane asks her to say it “in Earthling.” She does, sort of, and then Frost asks for “even more Earthling.” She opts for the show-don’t-tell approach and causes a little lab explosion to demonstrate. The firefighter’s mask and gloves were coated in a combustible compound and then douses to start the high-intensity fire. And the same compound was found on the floor mats. So they realize the killer was in the fire with him. So they zero in on the other firefighters in Engine Co. 15. Seems someone else in the company was suspicious about the company, and it was the deceased firefighter. He was investigating all of their fire calls. And he was about to uncover that while they were all ruled accidental, they were set around the same time and day. So they need to flush out the firefighter who started them.
And they’re going to use Maura as bait. So Maura creeps around the burned out factory in her kicky boots and the bad firefighter comes to finish her off. He says he set all those fires to show the public and city it can’t keep laying off firefighters, or something. Luckily Jane, Frost, Korsak and Frankie are also there. As is Gabriel, much to Jane’s chagrin. But then, just as the bad fireman is about to pull his gun on Maura, Doyle emerges from nowhere and guns him down to save his daughter. Gabriel then pops out and tells Doyle to drop his weapon.
Jane screams “No!” at him. He shoots Doyle. Doyle shoots him. Jane and raises her gun at Doyle. Now it’s Maura’s turn to scream “No!” But then Jane shoots Doyle. Doyle falls from the catwalk onto the ground floor and Maura runs to him. Jane is close behind, screaming Maura’s name. Doyle says, “Hope” with what is probably his last breathe. Jane goes to put her jacket under Doyle’s head and Maura snaps at her “Don’t touch him! No, I mean it, don’t you dare touch him!” The episode ends.