Numb3rs is a crime drama about the application of mathematics in criminal investigations. More specifically, the show is about an FBI agent and his mathematical-genius brother who work in tandem to solve some of Los Angles' toughest federal criminal cases. It is a unique approach for a procedural crime drama, which works pretty well. For more details about the series, refer to DVD Talk's reviews of season one, season two, and season three.

Like many other television series from 2007 to 2008, Numb3rs' fourth season did not have a full bill of episodes. The Writers' Guild strike resulted in only twelve episodes airing. However, after the strike the show returned with six more episodes, totaling eighteen for season four. While a shorter than usual season, there are a number of strong episodes and developments that fans will want to check out. The tempo is similar to past seasons with math being an important part. In addition, there are a lot of new developments for characters and their relationships.

Season four opens with "Trust Metric", which is the conclusion to the wild plotline from the season three finale. Colby was revealed as a double agent working for the Chinese and put into jail with co-conspirator Dwayne Carter (Shawn Hatosy). In "Trust Metric", he and Dwayne escape from custody. While on the run, Don and team chase after him again. The team also deals with the outcome of such a close friend being a traitor. However, as it turns out, the situation is not black and white. They uncover a shocking revelation. Val Kilmer guest stars as Mason Lancer, the big bad guy in charge.

As the season continues, the team works on a number of tricky cases, where math is a key part to solving them. "In Security" is a pretty strong episode, where Don's actions are put into question. People in witness protection are being murdered. Around the same time, Don visits a friend in witness protection. She is murdered and all signs point to Don being at fault. Charlie uses regression analysis to prove Don's innocence. The case takes a turn for the worse when it becomes apparent their might be a mole. "Tabu" is a good episode with a twist. Ella Pierce is the heiress to a wealthy empire (think Paris Hilton). While at a popular night club, she is kidnapped by People's National Agenda. When the ransom comes forward, Ella's father takes charge and refuses to pay. As the case unfolds, Charlie uses math to locate their hideout. The situation itself is complicated when it becomes apparent who was behind the kidnapping.

"Black Swan" is an exciting story with terrorists. Don's team raids a meth lab and finds a suspicious person at the scene. After investigating his van, they find weapons and other assorted goods. They do not know what he was planning, but with the help of Charlie and graph theory, they identify where he had been. It turns out he was working with a small group of domestic terrorists. Don and team rush against the clock to stop them from enacting their plan. "When Worlds Collide" is the season finale and a strong way to close out the season. Don's team gets their sights set on the Pakistan Regional Fund. Charlie takes it personal, as his friend Phil Sanjrani is one of the suspects. The conflict puts brother against brother. It is a pretty intense storyline, as it does not end well for everyone.

As for other season developments, there are a lot of new things on the horizon for the cast. Megan returns for the entire season. In season three, she was temporarily assigned to a special task force with the DOJ. She came back a different person -- darker. She gets a little too personal on a number of cases and makes a startling career decision when it becomes too much for her to handle. She and Larry also rekindle their romance. Larry continues life at the monastery, but eventually returns to CalSci when offered a lucrative position. Don and Liz's relationship goes sour and she leaves the team, but helps out on a few occasions. Don's ex Robin comes back into the picture. Charlie and Amita's relationship gets more serious. Alan becomes a Cal Sci student. Charlie also publishes about book about math and relationships, which becomes pretty popular.

Overall, Numb3rs' fourth season is strong. It starts off with an intense episode about treason, double-agents, and a lot of mistrust. As the season continued, the stories proved to be enjoyable with a nice balance of drama, action, mystery, and math (which gives the show its unique edge). In addition, there is decent comedy and a solid cast dynamic. In the end, fans will not be disappointed with season four.

Episode Guide

1. Trusted Metric: Was Special Agent Colby Granger really a double agent working for the Chinese? Don and his FBI team have been reeling at that stunning revelation... but an even greater surprise is in store when Colby escapes from prison and they attempt to track him down. Val Kilmer guest stars.
2. Hollywood Homicide: Colby is back on the job, but only temporarily until he is reassigned. When charismatic up-and-coming movie star Brett Chandler is implicated in the murder of a young woman, Don and the team, including Colby, are thrown into the dizzying world of a Hollywood entourage.
3. Velocity: As Colby prepares to be reassigned, Don and his team investigate the case of an out-of-control car driven by a teenager that smashed into a coffee shop, leaving one person dead and many others injured.
4. Thirteen: The team embarks on a desperate hunt for a sinister serial killer who is obsessed with replicating the deaths of Jesus Christ's apostles - and leaves Bible verses behind at the site of each murder.
5. Robin Hood: A bank vault laden with safety deposit boxes is broken into and looted by an apparent "Do-Good" bandit. Meanwhile, physics professor Larry Fleinhardt mulls over the possibility of leaving the monastery.
6. In Sercurity: A case hits close to home when a woman in a Witness Protection Program - with whom Don once had an affair - is found murdered; he fears he may have led the killer right to her.
7. Primacy: Professor Amita Ramanujan, a secret alternate reality game player, is forced to introduced the team to the obsessive world of video gamers after a man plunges to his death while participating in one such game.
8. Tabu: An extremist group targets an heiress for abduction in order to punish her industrialist father. But after she is kidnapped, he refuses to negotiate with the suspects to try to win her release. William Atherton guest stars.
9. Graphic: Agent David Sinclair, an avid comic book collector, takes special interest in a case in which a deadly robbery leads to the disappearance of an extremely rare comic - and forgeries of the covered item quickly start to surface. Christopher Lloyd and Wil Wheaton guest star.
10. Chinese Box: With David trapped in a stalled elevator with a paranoid, gun-wilding shooter, Megan and Liz rush to validate the apparent madman's claim that an agent at the FBI offices had placed him under surveillance.
11. Breaking Point: After appearing in a news report about the FBI's involvement in the case of a missing investigative journalist, Charlie becomes the target of a thuggish intimidation, which inhibits his ability to perform his math.
12. Power: The team must track down a serial rapist who is using his position as a police officer to ensnare and then assault his victims.
13. Black Swan: A raid on an inner-city meth lab also nets a bystander, whose van is filled with guns and other suspicious items. Has Don and his team unintentionally stumbled upon a member of a terrorist cell that is planning an attack on Los Angeles?
14. Checkmate: Don's old flame Robin Brooks returns to California to prosecute incarcerated criminal kingpin Jarobi "J-Light" Taylor. Don and his team get involved in the case when three key witnesses are murdered, and it's discovered that Robin is the next victim.
15. End Game: Clay Porter's father and sister are taken hostage by a gang of military thieves, forcing him to return from hiding in Mexico for the murders he allegedly committed in the U.S. Don's team uncovers the motive behind these kidnappings, revealing that the military thieves need Clay because they believe he knows the location of stolen money in Iraq.
16. Atomic No. 33: A mass poisoning at a cult compound - with the affected members refusing treatment - leads Don and his FBI team into a maze of old grudges and a complex murder plot.
17. Pay To Play: While investigating the murder of a rap star, the team uncovers a conspiracy of embezzlement and bribery that may be connected to the popular musician's death. Juicy J and DJ Paul, of the award-winning rap group Three 6 Mafia guest star.
18. When Worlds Collide: Don and Charlie find themselves in conflict over their differing beliefs as they investigate a case involving national security, while Megan, facing a crisis of conscience, makes a startling career decision. Zeljko Ivanek guest stars.

The DVD

Video:
The video in this release is given in an enhanced anamorphic 1.78:1 ratio widescreen color format. The picture quality is quite good. It suffers from a slight grain, but detail remains to be sharp and clear. However, there are some occasional moments when the picture suffers compression artifacts. This is a rare occurrence, but it does happen.

Audio:
The audio track in this release is in English 5.1 Dolby digital surround. There is also a 2.0 stereo track included. In general, the sound quality is very good and it provides an audible and clean track. The dialogue is usually a little flat while music and sound effects come off rich and vibrant. Additionally the 5.1 track is dynamic and makes good use of the surround sound capability. There are no subtitles, but the release supports closed captioning.

Extras:
Crunching NUMB3RS: Trust Metric (54:54): is a five part featurette about the making of the episode "Trust Metric". The sub-featurettes include "Pre-Production", "The Tony Touch", "The Ambush", "The Freighter", and "Post Production". The discussion includes cast and crew talking about the storyline, production issues, critical scenes, etc.

Final Thoughts:
Numb3rs is a television crime-drama that takes a different approach than other series in the genre. The show uses mathematics to solve tough federal crimes. The approach provides a unique and intriguing appeal. As for season four, it has a lot of exciting developments. The season starts with a great episode and concludes with an intense finale. In between the opener and the finale, there are a number of entertaining episodes. Fans will not want to miss out on it.

Also, if you are interested in learning about the mathematics used in each episode, refer to the Numb3rs blog, which is maintained by Professor Mark Bridger, Northeastern University, Department of Mathematics. The blog provides detailed explanations for the mathematical concepts and theories behind Numb3rs.