In the Book In the Movie

Angier and Borden clash in the dark during the course of a fraudulent seance and become enemies. Angier and Borden both work for Milton the Magician. Angier's wife is killed during an illusion and Angier blames Borden for using a difficult knot. They become enemies after that.

Angier uses Tesla's machine to create a new act called "In a Flash" He calls his act "The Real Transported Man"

When Tesla's machine is used, after the subject is transported, the original subject becomes lifeless. So when Angier uses it his body drops lifelessly and must be disposed of. When the machine is used, a complete clone is transported, so the original continues to live. This original is then drowned by Angier in a tank of water.

Borden attempts to discover Angier's secret for In a Flash. He turns off the machine during the teleportation which results in the two Angiers. Borden tries to discover the secret to The Real Transported Man, and watches beneath the stage as Angier falls through a trap door and into a tank of water. As Angier is drowning, Borden attempts to save him, but fails. He is arrested, tried and convicted of Borden's murder. He is hanged.