A bomb blast that rips through the locker room at a gym is linked to similar bombs that killed a young employee at a big box store in 1999, blinds a father and husband in 2001 and then kills a man at a hospital in 2003. The detectives soon realize they have a serial bomber on their hands and must protect his next target before the bomber gets to him first. Meanwhile Scotty and ADA Thomas take some tentative steps in their relationship.
A present day pipe bombing shows similar characteristics to three prior pipe bombings all of which took place in the last nine years. The evidence is lacking with two dead victims and two critically maimed who share no common denominator.
The bomb device turns out to be a music box that plays the song ”John Henry”, an American song standard about man versus machine, leading the detectives to believe the bomber may be anti-establishment. After a lead brings them to what they believe may be the bomber’s apartment they discover pictures of all the victims. However, one picture proves the bomber in his latest attempt missed his intended target.
Putting that man under protection the detectives slowly start to figure who the mysterious bomber may be after interviewing the surviving victims. The bomber, a man who had lost his home, his job and his family slowly spiraled out of control. Feeling abandoned by the establishment and his own brother who he felt had turned against him and the legacy of their family’s home where they grew up by not stopping it from being torn down, he decides to take what his brother loves most and plants a bomb in his brother’s home. But the detectives manage to figure out what he was up to and save the family from the explosion
- Kathryn Morris as Lilly Rush
- Danny Pino as Scotty Valens
- John Finn as John Stillman
- Jeremy Ratchford as Nick Vera
- Thom Barry as Will Jeffries
- Tracie Thoms as Kat Miller
- Kim Coates as Alessandro Rossilini
- Chris Butler as Roderick Poole
- Kate Jennings Grant as Beth Ross
- Ryan Kelley as Curt Fitzpatrick
- Bob Koherr as Carl Baxter
- Timothy Omundson as Luke Ross
- Stephanie Venditto as Helen Wainwright
- John Hillner as Gene Schmidt
- Judyann Elder as Cecilia
- Alexis Krause as Gina Castello
- Roberto Montesinos as Angel Perez
- Doug Spinuzza as Louie Amante
- Alessandro's anti-technology agenda and his troubled relationship with his married younger brother are apparently based on Theodore Kaczynski, better known as the "Unabomber". The real Kaczynski was mentioned by Joseph Shaw in the episode "Joseph".
- Rita Baxter's then-unsolved case box is visible just below Curt's case box when Curt's box is first put away.
- Wham! "Last Christmas"
- Red Hot Chili Peppers "Snow"
- Live "Turn My Head"
- The Smashing Pumpkins "Crestfallen"
- Closing Song: OneRepublic "Apologize"