Abraham Lincoln is relieved that Richmond has fallen and the U.S. Civil War is effectively over. He has contentious discussions with his Cabinet about the treatment of the defeated Confederacy. Many members of his cabinet want the Confederates punished, but Lincoln argues for mercy. He is despised by many Confederates and receives numerous death threats. Lincoln has a rather fatalistic attitude about them but as a disturbing dream about hearing cries in the White House and seeing a coffin in the East Room surrounded by mourners crying out that an assassin has murdered the President. Booth is the most popular actor in the country (it is pointed out that only Lincoln has his picture taken more often).
Coming from an acting family, he feels overshadowed by his father and brother and longs to make his mark on history. A fanatical Confederate sympathizer, Booth sees Lincoln as a tyrant and slavery as a proper way of life and assembles a motley group of Confederates, including former Soldier Lewis Powell and simple-minded David Herold. They form a plot to kidnap the President, but the war ends on April 9. Two days later, on April 11, Booth is outraged when he hears Lincoln making a speech promising African-Americans citizenship and the vote. His changes his plot from kidnapping to murder.
Eventually, on April 14, Booth decided to assassinate Lincoln at Ford's Theatre, orders Powell to kill Secretary of State William Seward, and orders another henchman, George Adzerodt, to kill Vice President Andrew Johnson at the Kirkwood Hotel. Later that night, during the performance of Our American Cousin at Ford's Theater, Booth shoots Lincoln and escapes after stabbing the left arm of Major Henry Rathbone, a substitute guest, and landed awkwardly on the stage. Almost the same time that happens, Powell attacks Secretary Seward at his mansion. Though seriously disfigured by Powell, the metal canvas split saved Seward's life. Meanwhile, at the Kirkwood Hotel, Vice President Johnson is unharmed because Adzerodt couldn't have the courage to shoot him. Back at Ford's Theater Lincoln is attended by the doctors who were actually in the theater. After being examined by Dr. Charles Leale and two other doctors, Lincoln is then carried across the street to the Petersen House, where he died the following morning at 7:22 A.M. surrounded by his friends and family for the remaining 8 hours. After an intense manhunt for two weeks, Boston Corbett shoots Booth inside a burning barn surrounded by federal troops. After clinging to life for less than three hours, Booth dies on the front porch after saying that he died for his country.
The credits reveal that four of Booth's henchmen and Mary Surratt were put on trial and hanged. Ironically, Lincoln's successor Johnson was much harsher on the defeated South than Lincoln would have been.