An explosion during a protest leads to Beckett and Castle recreating the timeline that led up to this tragedy.
A bomb explodes at a Wall Street Protest, killing 5 people.
Using advanced technology from the feds, the detectives trace GPS from cell phones who were in the vicinity.
The explosion was caught on live news from a newscaster.
A cell phone picture shows the location of the bomb 47 seconds prior with nothing there. The detectives break down the 47 second to find the bomber.
One of the victims who was heavily involved in the cause built a bomb that was meant to just bring attention, not to hurt anyone. The newscaster was his partner, setting off the bomb and hoping to get noticed by her network.
While interrogating a suspect, Beckett says she remembers every second of the day she got shot. Castle overhears and is now angry that she has lied to him.