Travis Owen confesses to Father Danskin that it's too late. Before the Father realizes, the church is on fire and Travis places a crowbar blocking the pew door. Father Danskin dies in the ensuing fire. Nash arrives too late, but Angel is there as a witness. Nash and Joe look around the crowd, suspecting that the arsonist is there in the crowd.
At headquarters the next day, Joe briefs the SIU on plans for Nash's surprise birthday party. Caitlin moves in permanently for a full audit investigation of SIU cases. Rick Bettina asks Caitlin for a date to the party, but is turned down. An electrician searches for the source of the mysterious disco, smoke and light show that comes on suddenly on the boat, formerly a rave club.
The fire was professionally set with phosphorous, igniter, and timer. Nash suspects Dante Rollins, known arsonist. They visit Rollins at the hospital, where Rollins has been burned from head to toe in an accident. Rollins reveals that he sold phosphorous, enough to start 6 or 7 fires, to an unknown person.
Harvey and Evan check out another suspicious fire and spot Travis Owen in the crowd. Evan arrests Owen, but he resists and puts up a fight forcing Evan to physically assault him.
Angel identifies Owen. Caitlin investigates Owen's charges of police brutality against Evan, and she decides to go after Evan. Further facts surface - Owen was a member of the church he torched, he also worked for the construction site which was torched. Jeff Bellamy is architect for the site.
Harvey and Evan go to Owen's home but the garage is booby trapped, engulfing a uniformed policeman in flames. A search of Owen's personal possessions reveals numerous photographs of a girl named Laura. Owen is apparently infatuated with Laura, and has told his grandmother fabrications about how Owen and Laura Smith eloped. Meanwhile, Owen has rigged a firebomb in Jeff Bellamy's office computer.
Caitlin continues to gather evidence against Evan, including an old complaint filed by a Mr. Fortner in 1995. Nash confronts her, and tells her to leave his men alone. Laura Smith barely recalls Owen from a bad date they had three years ago - her fiancé is architect Jeff Bellamy. Owen has her photographs because she develops them at the pharmacy where Owen works. At Jeffrey's office, Owen's phone detonator doesn't work. When Owen goes into the office, Nash, the SIU, and SWAT are waiting for Owen.
Meanwhile, Evan and Cassidy are re-united romantically while shopping for party stuff. Rick Bettina has shown up for Nash's party at the wrong decoy location because of deliberately misleading information given to him by Joe. Caitlin has lost her wallet; she blames it on Nash as a hazing prank pulled on her. But it is really Angel who has taken her wallet as a means of bringing Nash and Caitlin together when Nash goes to return her wallet. Sparks fly but Nash must leave with Nick and Cassidy to go to his "surprise" birthday party.
For more, see commentary for Episode 63