As the player, you become Geralt and your decision leads to different outcomes.
https://www.youtube.com/watch?v=WwCXw8m0PHIVideo can't be loaded because JavaScript is disabled: The Witcher 2 – Enhanced Edition – X360 – Letho: The return of the kingslayer (https://www.youtube.com/watch?v=WwCXw8m0PHI)
The Witcher 2: Assassins of Kings is a direct sequel that begins with Geralt accused of murdering a king[...]