"Homeland" Season 1 introduces Carrie Mathison, a brilliant but volatile CIA officer who suspects that Nicholas Brody, a U.S. Marine Sergeant rescued after eight years as a POW, has been turned by al-Qaeda and poses a threat to national security. Brody, hailed as a war hero, struggles to reintegrate with his family, including his wife Jessica. Carrie, often operating outside protocol with the help of her mentor Saul Berenson, begins an unauthorized surveillance of Brody, convinced he is a sleeper agent for terrorist leader Abu Nazir.

Carrie's investigation intensifies as she uncovers suspicious behavior from Brody, including his secret conversion to Islam. A major turning point occurs with the shocking revelation that Tom Walker, the other Marine captured alongside Brody, is alive and also working for Abu Nazir, disproving Brody's earlier claims. Brody is then recruited to run for Congress, bringing him closer to his target, Vice President William Walden. Carrie's relentless pursuit of the truth leads to her erratic behavior being exploited by Brody, resulting in Carrie being fired from the CIA.

In the season's climax, Brody prepares to detonate a suicide vest at a summit attended by the Vice President. Carrie, despite her professional downfall, pieces together the plot and manages to intervene by contacting Brody's daughter, Dana, who convinces him to abort the mission. As a final act of loyalty to Nazir, Brody then kills Tom Walker, eliminating a loose end. The season concludes with Carrie undergoing electroshock therapy, potentially erasing her memories of the events, unaware that she successfully thwarted a major terrorist attack.

Season 1 of Homeland covers episodes 1-12. Here's everything that happened:

Season 1, Episode 1: Pilot - Carrie Mathison suspects newly rescued POW Nicholas Brody is a sleeper agent. Brody returns home to his family, but struggles to readjust. Carrie illegally surveils Brody, noticing a potential coded message. The episode concludes with Brody's flashback revealing he murdered a fellow prisoner, under orders.

Season 1, Episode 2: Grace - Carrie continues her surveillance of Brody, who struggles with PTSD, experiencing vivid nightmares. Carrie gets a warrant to continue her surveillance. Her asset, Lynne, provides video evidence of Prince Farid meeting Abu Nazir, but protection for Lynne is denied. Brody later confronts the media in his military uniform.

Season 1, Episode 3: Clean Skin - Carrie's asset, Lynne, successfully downloads data from Prince Farid's phone, but is murdered by his associate for a diamond necklace used to fund a terrorist plot. Brody's family prepares for a TV interview amidst rising tensions, and Dana confronts her mother about her affair. The episode concludes with Carrie lamenting Lynne's death and the realization that the necklace financed a couple buying a house near the airport, hinting at a future attack.

Season 1, Episode 4: Semper I - Carrie's surveillance warrant nears expiration as Brody's public image grows, worrying his wife. Brody's erratic behavior culminates in him shooting a deer at a party. Carrie removes the surveillance equipment and follows Brody to a church meeting, where they "accidentally" meet. The episode concludes with Carrie and Brody engaging in heavy flirting.

Season 1, Episode 5: Blind Spot - Carrie and Saul interrogate Hamid, a terrorist, with Brody's help. Brody requests a private meeting with Hamid, which Estes approves. Hamid is later found dead, having committed suicide with a razor blade. Carrie suspects Brody's involvement and that he warned another terrorist, Faisel, who subsequently disappears. The episode concludes with Carrie's suspicions deepening and relationships fracturing.

Season 1, Episode 6: The Good Soldier - Carrie proposes polygraph tests for those who contacted Hamid, including Brody, after Hamid's suicide. Faisel is killed in a shootout, while Aileen escapes. Brody passes the polygraph, even when questioned about infidelity. The episode concludes with Carrie getting into Brody's car.

Season 1, Episode 7: The Weekend - Carrie and Brody escape to a cabin, complicating their relationship as Carrie's suspicions intensify. Saul apprehends Aileen, gaining crucial intel about a visitor to her house. Carrie confronts Brody, revealing her surveillance, leading to Brody admitting his conversion to Islam. Saul discovers Tom Walker is alive, disproving Brody's story..

Season 1, Episode 8: Achilles Heel - Walker is alive and in contact with a Saudi diplomat. Carrie tells Brody, who then confronts the diplomat. The FBI chases Walker into a mosque, resulting in the accidental deaths of two innocent Muslims. Walker retrieves a sniper rifle. Brody tells the diplomat he is done with Nazir.

Season 1, Episode 9: Crossfire - Carrie pressures the FBI to admit fault in the mosque shooting to gain the Imam's cooperation. Brody is abducted and confronted by Abu Nazir, who reminds him of his motivations. Walker kills a hunter who recognizes him. Carrie learns of Walker's contact with a Saudi diplomat. The episode concludes with Jessica informing Brody that the Vice President's office called.

Season 1, Episode 10: Representative Brody - Walden recruits Brody to run for Congress. Carrie and Saul pressure diplomat al-Zahrani, who reveals Walker's planned meeting. Brody confirms with Carrie that their affair remains secret. At Farragut Square, a suicide bomber kills al-Zahrani and injures Carrie. Saul suspects a mole, while Brody announces his candidacy.

Season 1, Episode 11: The Vest - Brody retrieves a suicide vest in Gettysburg while on a family trip. Carrie's erratic behavior following the explosion leads to a manic episode, but she uncovers a key period of inactivity in Nazir's timeline. Brody manipulates Estes, resulting in Carrie being fired after he confesses to their affair and accuses her of harassment. The episode concludes with Carrie losing her job and Brody closer to his mission.

Season 1, Episode 12: Marine One - Brody plans to detonate a bomb at the Vice President's summit, but Carrie convinces Dana to call him, leading him to abort the mission. Walker is then killed by Brody. Carrie undergoes electroshock therapy, potentially erasing her memories, unaware she stopped the attack.