Stories about child molesters and his own experiences as a parent inspired series writer Don McGill to write the episode.
Child molester John Santos (Ray Torres) is found tied to a chair and beaten to death in a vacant house up for sale, the third such victim in the past six weeks.
Meanwhile, Dr. Larry Fleinhardt (Peter MacNicol) prepares for his upcoming mission to the International Space Station, which he learned some time earlier that he would be a participant in.
FBI Special Agent Don Eppes (Rob Morrow) calls in Charlie and Larry for their assistance.
FBI Special Agent Megan Reeves (Diane Farr) interview the first victim's wife, Mrs. Elaine Tillman (Robin Weigert), who denies any knowledge of her husband's online activities.
FBI Special Agent David Sinclair (Alimi Ballard) and Colby Granger (Dylan Bruno) take Brendan McCrary (George Newbern), a frequent visitor in the chat room that the molesters used, into custody.
He learns that McCrary's son Matt (Johnny Simmons) thought that his family was not doing enough to stop molesters after what happened to his sister, so Matt contacted someone in an online support group for families affected by sexual predators to discuss non-violent ways of vengeance.
He also gave them the names and contact information of predators that his father was investigating, but he swears that he didn't know they were going to be tortured and killed and is horrified that he was an accessory to murder.
Megan convinces Mrs. Tillman to surrender peacefully by promising that the molester will be prosecuted to the fullest extent of the law, because there was enough evidence to convict him of his crimes, and the agents arrest both people.
[3] To send off MacNicol's character, the creators and producers decided to ask a real astronaut to appear on the show.
[3] Originally, the technique was to be included in the previous episode "Brutus", but, due to the complexity of the topic, it never made it into the script.
[3] McGill wanted to use a "trawling algorithm", a way to catch an online identity that is hidden by Internet encryption.
[3] During the early phases of writing the script, McGill told Black that Charlie was going to analyze crime scenes with no other commonalities between them other than they are empty houses.
[3] Before he directed the episode, director Chris Hardwell spent five weeks on the Numb3rs set watching the cast and crew film the series.
He also directed guest star Robin Weigert to act like the perfect housewife in order to disguise the plot twist.
MacNicol's last filmed scene was set toward the beginning of the episode when Charlie and Larry discussed using multi-attribute compositional modeling to determine the commonalities of the houses.
For MacNicol and series regular David Krumholtz, filming became emotional as the episode paralleled real life.