The body of an arson investigator is found shot to death inside of a burned building.Beckett and the team search for a serial arsonist who committed the murder.
Esposito and Ryan find the arsonists lab in an old warehouse but it's rigged to explode. With the building engulfed in flames they find themselves trapped in a sub-basement with no escape.
Jenny rushes to the scene, in labor. Kevin manages to place a phone call and talks to Jenny, thinking he's going to die. They agree to name the baby Javier if it's a boy and Sarah Grace after Jenny's grandmother if it's a girl.
Castle and Gates figure out that the arsonist had a secret escape route from the sub-basement. Beckett and Fire Inspector Burden realize that Building Inspector Mark Kimball checked on every building set on fire. They capture him and Beckett forces him to reveal the entrance to the basement.
Javier and Kevin are saved just as Lanie helps Jenny deliver little Sarah Grace Ryan in the back of an ambulance.