Michael Clayton, a "fixer" at a prestigious law firm in New York, specializes in cleaning up the legal messes of wealthy clients. With a failed business venture and a tumultuous personal life, Clayton is trapped in a job he has grown to despise. However, his skills and loyalty are unquestionable, making him an invaluable asset to the firm. When the firm’s leading litigator, Arthur Edens, has a breakdown during a deposition in a multi-billion dollar class action lawsuit against U/North, an agricultural products conglomerate accused of producing carcinogenic products, Clayton is called in to manage the situation. Edens, having discovered evidence that could destroy U/North, becomes a liability that Clayton must deal with.

As Clayton delves deeper into the case, he finds himself in a complex web of legal and moral dilemmas that force him to confront his own values and the corrupt nature of the legal system he serves. Meanwhile, Karen Crowder, U/North’s in-house chief counsel, is determined to protect her company’s interests at all costs. Her ruthless tactics set her on a collision course with Clayton, pushing him to a point where he must choose between his career and the pursuit of justice. With his expertise in navigating murky legal waters, Clayton embarks on a dangerous path that challenges his professional and personal integrity.