The viewer is introduced to the missing persons unit, headed up by the driven but morally compromised Jack Malone, whose professional successes are marred by his complicated personal life—he is in the midst of a messy breakup from his wife, precipitated by his own infidelity with his protégé, Samantha "Sam" Spade. At the outset of the series, Jack struggles to balance his crumbling marriage with the arrival of Martin Fitzgerald, a rookie agent whose placement Jack sees as a sinecure due to Fitzgerald's father being a powerful figure in the FBI. The team ultimately find themselves forced to come together and personally reckon with the legacy of 9/11 when a businesswoman whose company headquarters were destroyed in the Twin Tower attacks is kidnapped by a man whose wife was killed in the World Trade Center.