Muthr helped teach Eva the skills of preparing to leave the underground Sanctuary. When Eva is left alone in her bedroom, Muthr returns to her quarters (The Control Room) to look over and examine the building. When she was alerted that an intruder (Besteel) had entered the Sanctuary, she set out to find Eva, who turned up from a secret room in the facility. She brought Eva into the Kitchen, where she explained to Eva that she must flee the Sanctuary.
Eva and Muthr heard numerous messages regarding detected smoke in the Sanctuary. Muthr opened a hatch and ushered Eva to climb into it, but Eva refused to do so without her. She eventually got Eva to leave, however, when the intruder blast open the Kitchen door. Inadvertently, Muthr had caught fire and evaded the intruder. She ran into the gymnasium and jumped into a pool in order to put it out. The intruder then found Muthr and disabled her by stealing her battery, a Hyperion power cell.
Muthr is found in the Sanctuary by Eva and her blue friend, Rovender Kitt. She is taken into the Generator Room where she is powered up. Muthr awakens in a new crab-like body. Eva told Muthr that she rescued her in order to pursue her quest onto going to the next Sanctuary (HRP). Muthr explains to Eva she cannot leave the Sanctuary due to her duty.
Eva logs in as an official to the Sanctuary mainbase (C-P zero-one) and asks the Sanctuary to identify if Muthr is allowed to leave. The Sanctuary replies positively, just as Besteel returns to the Sanctuary in pursuit of Eva. Muthr, Rovender, and Eva escape the Sanctuary heading to a nearby abandoned Sanctuary, where Eva and Muthr find out they are on a planet called Orbona, not Earth.
Eva and Rovender then rest, as Muthr snaps holos through Identicapture with the Omnipod. They awaken and head out to the next Sanctuary though the underground tunnels. Muthr explains to Eva that she has to take about a month to get to the next Sanctuary. Eva says she wants to head out for her WondLa by going to the city of Solas, which Rovender had talked about. She said they must go through Lacus and all the way to Solas by ferry. Muthr finally agreed and they set out for Lacus. They then took a journey in the Wandering Forest, which lead them down to the city of Lacus.
Rovender, Eva, and Muthr arrive at Lacus, where a kind alien woman name Hostia (a friend of Rovender) invites them to stay at her hut while they avoid Besteel. Muthr is referred to as a toy by one of Hostia's sons, and misinterpreted as an evolved human by Hostia. Later that night, Hostia offers special drinks to the trio, which Muthr refuses due to the fact that she is a robot.
During a trek through the Wastelands, Besteel attacks Muthr, Eva, and Rovender. The huntsman aims his boomrod at Eva, but Muthr leaps in front in order to intercept the blast, which damaged her in the process. After Besteel had been defeated, Eva and Rovender returned to Muthr's ailing body. Muthr had told Eva that she was proud of her before shutting down completely; it is at this point she is pronounced dead.