The Witcher 2: Assassins of Kings contains many different paths and storylines , along with multiple endings. As in the first game, the player takes control of Geralt of Rivia, one of the few remaining Witchers. Witchers are humans that have been genetically enhanced and trained to fight monsters from a young age.
During the prologue, Geralt is interrogated in a prison of the kingdom of Temeria by Roche, the commander of a group of Temerian special forces known as the Blue Stripes, regarding the assassination of the king of Temeria, King Foltest. Geralt recounts the events leading up to Foltest's death, during which he acted as Foltest's bodyguard. During an uprising against Foltest by noble families of Temeria, Foltest personally leads the battle in order to recover his illegitimate children, Anais and Boussey, who are being held by the rebels. Once Foltest finds his children, he is killed by an assassin disguised as a blind monk, who escapes before Geralt can react. Geralt is then found by Temerian forces and mistaken for Foltest's killer. After hearing Geralt's confessions, Roche decides on Geralt's innocence and aids him in escaping the prison. The two then travel to a trading post named Flotsam, in search of the kingslayer.
Upon arrival to Flotsam, Geralt, Roche, and Triss are ambushed by Iorveth, with Triss's magic saving them from his archers. Geralt discovers the assassin is a witcher in league with a group of Elven rebels known as the Scoia'tael. The assassin is also revealed to have killed another king: Demavend, the king of neighboring kingdom Aedirn. Upon arrival, Geralt walks upon Zoltan and Dandelion about to be hung in the city square. After a scrap with the guards, the commandant of Flotsam, Loredo sets them free under certain conditions, and asks Geralt to meet him in his mansion. After him and Roche disable his ballista and find him hoarding merchant goods, Loredo tasks Geralt in killing the Kayran. After killing the Kayran disrupting the town's trade routes with Sile's help, Geralt meets a Scoia'tael lieutenant on the prison barge who claims the kingslayer, known as Letho, intends to betray Iorveth, the leader of the Scoia'tael. After confronting Iorveth with this information, Geralt and Iorveth decide to confront Letho, who reveals his plans to kill Iorveth. Before the two can capture Letho however, Roche arrives with an armed force. The player can make the choice of either assisting Iorveth (which results in the slaughter of nonhumans in Flotsam) or Roche (which results in Ioverth's capture and a feast in Flotsam). Geralt then engages in a duel with Letho. Geralt is defeated, but Letho spares his life after revealing that Geralt once saved the lives of Letho and his band of witchers. Letho then kidnaps Triss Merigold, a sorceress and Geralt's companion, and forces her to teleport both of them to Aedirn. The player now has a choice whether to assist Iorveth or Roche again, changing the path of the second chapter.
If Geralt assists Iorveth, the pair commandeer a prison barge and after either killing Loredo or saving the elven women in the prison tower he set fire to, set sail for upper Aedirn. There, a meeting is held between the king of neighboring kingdom Kaedwen, King Henselt, and a unified army of rebels, led by the deceased King Demavend's son, Prince Stennis, and a rebel commander known as Saskia the Dragonslayer. A fight breaks out, but is interrupted when an ancient curse is activated and spectral soldiers attack the humans. Geralt and Iorveth arrive just in time, assisting Saskia and Prince Stennis out of the battlefield, aided by the sorceress Philippa Eilhart, Saskia's advisor. The rebels then hold a meeting. Saskia intends to unite the loyalist forces under Prince Stennis, the dwarven forces of the town of Vergen, and the Scoia'tael, led by Iorveth, into a single fighting force and defeat King Henselt, then declare the formation of a free nation, led by Saskia herself as Queen. As the meeting nears adjournment however, Saskia is poisoned.
Geralt is tasked with two missions: recovering ingredients to formulate an antidote for Saskia, and recovering magical artifacts with which to lift the curse that has descended upon the battlefield. During the process, a mob of peasantry accuse Prince Stennis of poisioning Saskia, in which Geralt can either let the crowd kill him (and obtain his royal blood for the cure for Saskia) or let him set up a tribunal (in which Geralt gets royal blood from Henselt in his camp). With Geralt's help, Philippa Eilhart succeeds in curing Saskia. Geralt also discovers that Triss was abandoned by Letho upon arrival, and was subsequently found and captured by spies from the empire of Nilfgaard. Before Geralt can recover her, she is taken by the Nilfgaardian forces to Loc Muinne. Geralt then enters the battlefield himself to reenact a historic battle and end the curse. With the curse lifted, King Henselt and his forces attack Vergen, but the rebels defeat the Kaedweni army and Henselt is forced to acknowledge Saskia's terms. During the battle, Geralt discovers Saskia is actually a dragon taking human form. Iorveth notices that Saskia is acting strangely, ordering Dethmold to be executed without trial, but before he and Geralt can react Philippa teleports Saskia and herself to Loc Muinne. Geralt and Iorveth then discover that Philippa had placed a mind domination spell upon Saskia, and the pair has no choice but to follow her to Loc Muinne.
If Geralt assisted Roche however in Flotsam, Roche has Geralt assassinate Bernard Loredo, the commandant of the town for being a spy for Kaedwan (and in the process Ves helps a captive elf woman raped by Loredo give birth to a son, however she is unable to prevent the shattered woman's suicide). After leaving the elf's son with a caretaker, the Blue Stripes set sail for upper Aedirn. There, a meeting is held between the king of neighboring kingdom Kaedwen, King Henselt, and a unified army of rebels, led by the deceased King Demavend's son, Prince Stennis, and a rebel commander known as Saskia the Dragonslayer. A fight breaks out, but is interrupted when an ancient curse is activated and spectral soldiers attack the humans. Geralt and Roche arrive just in time, assisting King Henselt out of the battlefield, aided by Henselt's two advisors, the mage Dethmold and the sorceress Sile de Tansarville. Geralt is tasked by Henselt to lift the curse from the battlefield so that his forces can march on Vergen, as well as to lift another curse from Henselt himself, placed upon him by another sorceress, Sabrina Glessivig, whom Henselt had executed three years prior.
Geralt also discovers an insurgency within the Kaedweni army of loyalists convinced Henselt is conspiring with Nilfgaard, and continues his search for Triss. He discovers Triss has been taken by Nilfgaardian spies, but they leave for Loc Muinne before he can confront them. After lifting Sabrina's curse from Henselt, an attempt is made on the king's life by two witchers, Serrit and Auckes, in league with Letho. Geralt defends Henselt and kills Auckes. Using necromancy, Dethmold allows Geralt to delve into the dead witcher's memories, and Geralt discovers the kingslayers are in league with Sile de Tansarville, who has already fled to Loc Muinne, mortally wounding Serrit along the way. Geralt then lifts the curse from the battlefield, and Henselt begins his march. Roche turns out to be the leader of the insurgency within the Kaedweni army. Henselt and Dethmold, finding out about this, have every one of Roche's men under his command hanged, except for Ves (who was raped by Henselt himself). Geralt and Roche follow Henselt to Vergen. They arrive too late, and Sile de Tansarville and Philippa Eilhart escape to Loc Muinne, with the entranced Saskia in tow. Geralt and Roche defeat the remaining Kaedweni forces, and Geralt is given a choice to allow Roche to execute Henselt.
Finally, Geralt arrives at Loc Muinne, with either Iorveth or Roche depending on whom he assisted previously. The mages have called for a meeting at Loc Muinne to establish a new magical ruling body known as the Conclave. All royal leaders are thus meeting at Loc Muinne. Philippa Eilhart and Sile de Tansarville intend to use the meeting to establish their own power, and ordered the assassination of King Demavend to set in forth this chain of events. They intend to use the still-entranced Saskia as leverage at the meeting. Geralt discovers that Nilfgaardian spies are also at Loc Muinne, with Triss as their hostage. If Geralt arrived with Roche, he discovers that Foltest's illegitimate daughter, Princess Anais, has been kidnapped by Dethmold. He is given a choice between rescuing Triss or rescuing Anais. If Geralt arrived with Iorveth, he discovers that Philippa has been captured by the king of Redania, King Radovid, and her eyes put out by him. He is given a choice between rescuing Triss or rescuing the now blinded Philippa, who is the only person capable of lifting the spell from Saskia.
If Geralt rescues Anais with Roche, resulting in Roche brutally killing Dethmold in revenge, Geralt and Roche have a choice to send her either to King Radovid and the Redenians or John Natalis and the Temerians. If Geralt rescues Phillipa, she assists him and Ioverth in getting the dagger but escapes. If Triss is rescued, regardless of who Geralt assisted, results in the ambassador of Nilfgaard's death, as well as the revelations of the Lodge's involvement in the plot and Triss's role through Triss after she is rescued.
The meeting between the royal leaders and Sile de Tansarville commences. If Geralt assisted Saskia and Iorveth, Saskia declares her plan to create a free nation with herself as the Queen. If Geralt assisted Roche and chose to rescue Anais, either King Radovid takes her under his protection and declares Temeria a protectorate of Redania, or is put under Natalis's care until she becomes of age to rule. If Geralt assisted Roche and chose to rescue Triss, Roche will be declared an outlaw and the rule of Temeria will remain unsettled. However, the meeting is interrupted when Nilfgaardian forces arrive with Letho, who reveals the sorceresses' entire plot, or, if Geralt rescued Triss, the two arrive and then accuse Sile. Radovid then orders Sile's arrest, but she forces Saskia to revert to dragon form and escapes.
Geralt chases down Sile, but she manages to activate her teleportation device. However, the device has been tampered with by Letho, and will kill her instead. Geralt can choose to let her die or save her life and allow her to escape. Geralt then battles Saskia in dragon form and ultimately defeats her. If he assisted Saskia and Iorveth and chose to rescue Philippa, he is able to break the spell over Saskia's mind, otherwise he is given a choice between letting her live or finishing her off.
If Geralt rescues Triss, either Ioverth will be seriously wounded by Phillipa when attempting to secure her dagger and can be put into care by Triss or Roche, outlawed by attacking the Kaedwan camp alone, will have Anais and gets her to safety for the future of Temeria.
Geralt then finally confronts Letho, the kingslayer, who frees Triss from the Nilfgaardians if Geralt did not save her. Geralt can choose to talk to Letho, who then reveals a wealth of information. Letho is a witcher from the school of the viper in the south, along with Serrit and Auckes. The group was once saved by Geralt, and Geralt learns he turned over Yennefer of Vergenberg to their care. They eventually made their way into Nilfgaard, where they were given a deal by the Emperor of Nilfgaard, Emhyr var Emreis, to destabilize the Northern Kingdoms by assassinating kings. In exchange, the Emperor promised to build a new witcher school for them. With the witcher schools destroyed and the training techniques and mutagens of old lost, Geralt, Letho, and the remaining witchers are a dying breed, the last of their kind. Letho agreed, and the witchers arrived in Aedirn. There, they were hired by Sile de Tansarville and Philippa Eilhart to assassinate King Demavend. Letho then assassinated King Foltest and had the other witchers attempt to assassinate King Henselt, hoping to pin the further murders on the sorceresses as well. After hearing Letho's story, Geralt can either let him go or duel him to the death. Geralt then reunites with Triss and either Iorveth or Roche, and sets off to Nilfgaard to find Yennefer.
A concurrent plot of the game is the amnesiac Geralt's attempts to recover the lost memories of his previous life. After each major magical event, such as lifting the curse from upper Aedirn, Geralt recovers a few of his memories. He eventually remembers that he was slain when attempting to defend nonhumans from a pogrom. His body was recovered by Yennefer, who nursed him back to health. However, the two were attacked by wraiths led by the King of the Wild Hunt, who then kidnapped Yennefer. Geralt chases after the Wild Hunt and eventually recovers Yennefer, who similarly lost her memories as well. He then turned over Yennefer to Letho's care and continued his hunt, but was eventually defeated and left to die. He was then found by other witchers and taken to Kaer Morhen, thus beginning the events of the first game.