Jason Atwood was the former Deputy Director of the FBI. He initially aided his colleague, Hannah Wells in her investigation into the Capitol bombing, until his son, Luke, was kidnapped and held hostage by an unknown female conspirator. Under instructions from her in order to ensure Luke's safety, he falsely confessed to the murder of the Al-Sakar leader, Majid Nassar and was imprisoned. He was released from custody, but he was fired. He began directly aiding Hannah in her investigation into the conspiracy once Luke's killer was identified. However, Jason was caught spying on top conspirators Jay Whitaker and Patrick Lloyd and was shot by Nestor Lozano.
Just moments after the Capitol exploded, Jason was presented by Hannah Wells with the theory that the perpetrators responsible did not claim credit because they were not finished with whatever they were doing. However, when President Kirkman asked him for any suspects, Jason stated that they primarily suspected Al-Sakar. When Hannah confronted him for not telling the President about her theory, he replied that if she wanted him to, she had to prove it.
Jason did not get directly involved with Hannah's investigation until she showed him the existence of Room 105; a secret bomb shelter Congressman Peter MacLeish was hiding in during the attack. He went to report the discovery to President Kirkman, but due to MacLeish's sudden presence, he simply told that they were making progress.
After Majid Nassar was apprehended, Jason, along with Hannah interrogated him. They both discovered that he was set up to claim responsibility for the attack by a man called "Catalan". Unfortunately, that was all the information they got from him, because Nassar was assassinated hours after.
On a later evening, Jason was confronted by a mysterious woman who had Luke hostage. Jason drew out a gun and demanded Luke's location, only to put away the gun after she told that Luke would die if she was harmed. He was handed a phone to await further instructions from the woman.
The following day, Atwood met the mysterious woman. She then instructed him to falsely confess to assassinating Majid Nassar. After he complied with the woman's orders, he was incarcerated in a federal prison.
Weeks later, Hannah goes to Jason in an attempt to help her identify the mysterious woman who was blackmailing Jason. Afraid of putting his son in further danger, Jason did not provide any further information to Hannah on the mysterious woman. It was later revealed that the woman did not hold up her end of the bargain as she killed Luke and his body was found in a river. Atwood is later then released from prison although he was fired from the FBI. Jason and Yvette later had a funeral for Luke.
Some time later, Hannah identified the mysterious woman: Brooke Mathison. After Wells identified her, Atwood decided to find and arrest her. However, Hannah and Brooke engaged in a fight but Jason ended up saving her. Jason and Hannah were then forced to shoot and kill Mathison after she attempted to shoot Jason. Hannah and Jason then discovered a missile silo in North Dakota. However, they soon realized that Catalan somehow faked his death. The two fled back to D.C.
Some time later, Jason was shown spying on Patrick Lloyd, the head of the True Believers. He took photos of him and Jay Whitaker, another conspirator. However, Catalan spotted him and shot him to death using a silenced pistol.
In the end, however, his death was not in vain. By sending Hannah several images depicting Whitaker and Lloyd together, as well as a voice recording, Whitaker was smoked out as the White House traitor and arrested, and Lloyd was forced to go on the run abroad.