It is Sam and Jules' wedding. After they exchange their vows, Jules then kisses him. After the kiss, Jules announces to all of their guests that they are expecting and she is three months pregnant.
Some time later, a mysterious package is discovered at a 911 dispatch office and they call SRU. Spike determines it to be a bomb. But as they are evacuating the building, another bomb goes off at the Health and Welfare center. Ed, Jules, Leah and Sam divert to assist. Greg then declares that they're looking at a coordinated terror attack.
As Team One scrambles to contain the situation, the dispatch receives a call from a man claiming responsibility. He claims that there are more bombs but refuses to identify himself.
At the Health and Welfare center, the Team sorts out the dead from the wounded. They then learn that there are kids trapped inside the center's day care. Unfortunately, the only hallway leading there has collapsed with a small unstable hole. Jules volunteers to go in, despite Sam's protests. Jules asks if he's her teammate or husband. Sam consents to letting her go. Jules goes in and saves the kids. During the rescue, Jules cuts her leg on rebar while crawling through debris and is told by the paramedic treating her afterward that she needs to rest her leg.
Another bomb goes off at city hall, just as Clark arrives there to get a permit for his and Dean's outdoor prom. The city goes into a state of panic. With the mayor injured in the blast, Greg chooses to address the city, encouraging them not to embrace fear.
A vid is soon released from the perpetrator, spewing his anti-government theories. Spike can't identify him but discovers the number of his cellphone, tracing it to an Anson Holt, a school psychologist with negative views on society and was laid off for unknown reasons. The Team storms his house only to find it empty, but finds books on sadism and recorded CDs. Jules, who has been evaluating the video, realizes that there are ten targets that match the ten pillars of society that the perpetrator discusses in his video. The team believes that Anson Holt is going to target the lab he once worked in.
Ed receives a call from Clark, who is trapped in the parking garage underneath city hall. He pleads his son to stay strong as Team Three goes to rescue him. However, Ed urges them to go after Anson, who they trace back to his old office. EMS then takes their place in searching for Clark, including EMS member Steve from Seasons 3-4. Ed arrives on scene, hoping to find his son.
Team Three locates Holt, finding him watching all the carnage on the news and with an explosive vest on him. Donna Sabine orders all but one of her team out. Though Spike insists she waits till he gets there, Sabine insists she can disable the bomb. However, she can find no detonator and realizes that Holt is staring at an activated security camera. Holt is not the mastermind, but a pawn. Greg orders her to get out of there. As Donna and her teammate make a break for it, Holt screams horrificly, and the lab explodes. The episode ends with the death of Donna and her teammate, several citizens dead from bomb blasts, someone watching surveillance of the lab exploding, and Ed frantically digging for Clark in the parking structure.
- Hugh Dillon as Ed Lane
- Amy Jo Johnson as Julianna 'Jules' Callaghan
- David Paetkau as Sam Braddock
- Sergio Di Zio as Mike 'Spike' Scarlatti
- Olunike Adeliyi as Leah Kerns
- Enrico Colantoni as Gregory 'Greg' Parker