Another synopsis can be found [url=http://marathon.bungie.org/story/ben_reiter_synopsis.html]here[/url]. Nice job Thanatos. If I may be so bold, I'd like to make one minor correction. Durandal and Tycho are not lesser than Leela. The three AI's perform tasks independent from each other. It is likely that no single AI is considered superior to the other two. When Marathon 1 begins, it appears that Leela is the least affected by the Pfhor attack (although the SO later learns that Durandal was not harmed in the least by the Pfhor). One could argue that Durandal is actually superior as he controls crew life support, a task of primary importance in successfully completing the Marathon's mission of colonization.

Marathon takes place in the year 2794 aboard a large, multi-generational colony spacecraft called the UESC (United Earth Space Council) Marathon. The ship was converted from Deimos, one of Mars' two moons. The plot of the story sets the player as a superhuman cyborg and focuses around an invasion of the ship by hostile extraterrestrial slavers called the Pfhor. The plot is primarily revealed through various computer interfaces called terminals. It is through these terminals as well that the player receives mission information from Leela, the ship's artificial intelligence, as well as Durandal and Tycho, the two lesser AIs aboard the Marathon. The first half of the game involves the player initiating a counterattack and sending a distress call to the planet Earth to warn them of the invasion. In this process, the player is kidnapped by Durandal, an Artificial Intelligence responsible for opening doors, kitchen maintenance and other functions aboard the ship. He achieves rampancy at the beginning of the game, a state that is described by a few terminals in the game and Durandal himself as the self-awareness of a computer system that permits a progression towards greater mental abilities. Leela eventually succumbs to the attacks of S'pht compilers, cybernetic alien creatures enslaved by the Pfhor that fight on their side until the conclusion of the game. Durandal takes her place and ends up as the Artificial Intelligence that assists the player. He eventually sends the player to explore the Pfhor ship to collect information about it.. It is eventually discovered that the S'pht are under the control of a cyborg on the ship. When the cyborg is destroyed by the player, the S'pht become free and a rebellion against the Pfhor begins. Leela gradually becomes stable and assists the player in the extermination of the last few hostile forces on the Marathon. Durandal leaves the Marathon and gains control of the Pfhor ship. Seventeen years have passed since the events of the first game. Durandal, one of the three AIs from the Marathon, sends the player and an army of ex-colonists to search the ruins of Lh'owon, the S'pht home-world. He does not mention what exactly he is looking for, although he does let it slip that the Pfhor are planning to attack Earth, and that being on Lh'owon may stall their advance. Marathon 2 brings many elements to the game that can be considered staples of the series such as: a Lh'owon-native species known as F'lickta, the mention of an ancient and mysterious race of advanced aliens called the Jjaro, and a clan of S'pht that avoided enslavement by the Pfhor - the S'pht'Kr. At the climax of the game, the Security Officer activates Thoth, an ancient Jjaro AI. Thoth then contacts the S'Pht'Kr, who in turn destroy the Pfhor armada. Prepare to be confused by Marathon Infinity though. I found it to be a hard story to follow.