Randall Ezno is a veteran Cerberus operative tasked with capturing aliens for study some time in 2186 during the Reaper War. Randall is an Infiltrator who received extensive upgrades to his biotic and tech abilities via use of neuronal implants, more than any other human test subject on his main station.

After completing a mission on an ice planet, Randall returns to the Barn, a Cerberus research space station. On his way to visit his advisor, Inali Renata, something goes wrong and turian soldiers begin attacking the facility. During the attack, Randall tries to contact Inali, but she's cut off by someone. Randall hurries to Inali's location to ensure she is safe. After fighting past the turian invaders, Randall is shocked to find Inali suffering through horrific experiments at the behest of the Director of the Barn.

Ezno eventually learns that his implants were supposed to indoctrinate him, but the process failed. When the the Cerberus Director from the Cerberus Space Station known as "Barn" discovers this, he deems Ezno as a liability and sends the Barn's security forces against him, and also abducts Ezno's handler Inali Renata for experimentation. After capturing Inali, the Director cuts off Randall from the organization. Randall vows revenge and goes in search of the Director, now having to fight past the facility's Cerberus defenses. Counting with the aid of a turian soldier he once captured for Cerberus, as well a volus hacker that was held prisioner in the Barn, they set off on a stolen shuttle to LV426, a nearby desert planet where a pickup signal from the Systems Alliance was caught, according to the volus. Unbeknownst to the trio, an ambush from Cerberus awaited for them.