AGIMUS was a sentient supercomputer who tricked a planet's inhabitants into fighting a century-long internal war by passing himself off as a supernatural being. The war ended in 2381 through the intervention of a team from the USS Cerritos, who disconnected "Lord" AGIMUS from his network of drones.
Ensigns Brad Boimler and Beckett Mariner knew about AGIMUS, but were unaware that the cargo container they were assigned to deliver to the Daystrom Institute in the shuttlecraft Yosemite held the "evil computer". En route, the Yosemite was caught by gravimetric shear and crashed on a nearby planet. Revealed to be within the damaged container, AGIMUS attempted to turn Boimler and Mariner against each other, in the hopes of manipulating one of them into connecting him to a larger system. After surreptitiously downloading the contents of Mariner's PADD, AGIMUS showed Boimler a recording of Mariner talking Commander Jack Ransom into pulling him from a mission to Dansk that he had been anticipating.
Arriving at a derelict starship, Boimler and Mariner argued about whether they should allow AGIMUS to help them reactivate the ship. Boimler stunned Mariner with a type 2 phaser and took AGIMUS to the bridge, where he apparently connected him to the navigation console to act as a substitute after AGIMUS assured that the ship's engines were still functional. AGIMUS then triumphantly announced his true intention of using the ship's materials to build a fleet of murder drones and conquer the star system. However, Boimler revealed that he had merely connected AGIMUS to the dimmer switch, and that he had only stunned Mariner to gain the computer's trust, so as to access his power cell and broadcast a distress signal. Outraged but impotent, AGIMUS flickered the bridge lights in a vain attempt to "blind" Boimler and Mariner.
After Mariner, Boimler, and AGIMUS were rescued by a Danube-class runabout, the computer claimed to have turned over a new leaf, deleted his "manipulative subroutines", and expressed a desire to join Starfleet and follow in Seven of Nine's footsteps as "AGIMUS of One". Regardless of his intentions, AGIMUS was soon secured in the Self-Aware Megalomaniacal Computer Storage at Daystrom, where he began arguing with the numerous other evil computers stored there. (LD: "Where Pleasant Fountains Lie")