Commander Shepard meets Doyle as she is trying to restore the water supply to the colony. Doyle is dismissive of Shepard's questions and directs the Commander to Fai Dan for inquiries about the colony. She appears to be much busier than the other colonists, and will not even turn to look at Shepard while she works. Doyle asks the commander to turn on the water valves in the tunnels as the system is inactive and the Normandy cannot ship in enough water to supply them.
Shepard can ask why Doyle has not done anything about the water situation herself. Doyle struggles to answer, saying she is hurting since the last geth attack and focusing on the water shortage makes the pain go away: whenever she tries to do anything else she feels worse.
As she is infected with spores, the Thorian may have given Doyle a 'standing order' to get water flowing again. Either the Thorian knows how essential water is to human well-being or, as a plant, the Thorian is short of water itself and needs Doyle to obtain it. If Shepard helps, the grateful Doyle hands over a reward.
Along with the other colonists, Doyle fights to defend the Thorian when Shepard returns from the ExoGeni Corporation building. She can either be killed, knocked out harmlessly with one of the gas grenades, or knocked out with a melee attack.
- Macha Doyle is voiced by Cree Summer.