He is first seen in a trunk kidnapped by Larry Sizemore. Larry forces Michael to work with him to get information out of the British consulate after killing Anson's family. Fiona manages to keep Larry distracted and kills him with a bomb. Detonating the bomb triggers a larger bomb, whose existence was completely unknown by Fiona, which destroys the consulate and kills some security personnel. Later, at Michael's loft, Anson reveals himself as the missing member of the Organization, and the fact that he had a random family killed to sell his own cover story. He blackmails Fiona Glenanne by framing her for the bombing, which would get her jailed or possibly deported for her crimes. Anson forces Michael to work for him in exchange for not giving the incriminating evidence to the government. It is also revealed that Michael's father, Frank Westen, was killed on Anson's orders since he became curious as to why Anson was interested in Michael.
In Scorched Earth, Michael manages to convince Agent Pearce of Anson's schemes that landed Fiona in prison. The team tracks Anson to a chemical plant. Michael catches and fights with him just as Anson is about to board a boat and flee the country. But Anson reveals a remote trigger for a bomb inside the plant, threatening to detonate it with Michael's team and civilians still inside. Michael regrettably has to release him, vowing to catch him.
In the episode "Shock Wave," Anson is finally caught by Michael's brother, Nate Westen at the Atlantic City Airport. While being held hostage by Nate and waiting for arrest he is killed by the sniper Tyler Gray, Nate is killed by the followthrough with Michael and the team being left shocked and horrified by Nate's murder.
Anson was a cold and calculating individual. As one of the founding members of the Organization, he was deeply involved in its operations and helped assess the potential use for new members. When the Organization was being taken apart by Michael Westen, Anson was able to fake his own death and portray a helpless psychologist taken hostage by Larry. He is willing to kill anyone, including civilians, to achieve his goals as evidenced by the bombing of his fake family as well as the attempted bombing of a plane to frame a spy team. As a brilliant psychologist he manipulates those around him by finding out who they love, who they trust, and what secrets they hide. Anson is even able to assist Michael when Sam is being hunted by a deranged Russian spy, correctly deducing that all the Russian spy wants is to go home and be valued for the horrific deeds he has committed in the name of his homeland. By interviewing Michael's mother and father in the years before his burn notice, Anson was able to determine that Michael was an excellent candidate to be used for the Organization. Anson is also a master planner, having multiple contingency plans in case something goes wrong in one of his schemes or if Michael tries to dig up dirt on him.