Teresa Lipan is a special operations field agent, former member of the Agency and a partner and close friend of Gabriel Logan. Lipan was one of the few people who assisted Logan in escaping from the clutches of the Agency and set up a small communications base in the Nevada Desert.
She was initially a member of the ATF (Bureau of Alcohol, Tobacco, Firearmes and Explosives) assigned in Western Montana to locate a downed FBI satellite. She ran into a pair of suspicious looking men in black pinned down by local survivalists. At first she assisted those men, who claimed to be FBI, fighting the survivalists and preventing Oakton from getting his hands on the satellite. A comrade of hers, ATF agent Demarco was pinned down by a number of survivalists, which she had to dispatch in order to rescue him. Whilst planting a homing beacon on the powerlines and afterwords arriving at the satelite crash site, where she meets Logan for the first time.
Logan warns her that the men in black are not FBI but NSA, and that they have orders only to retrieve the satellite data and kill the Oaktons. Teresa was advised by Logan to leave the area, however she decides to stay and investigate further. She had to remove the tracking beacon from the telephone pole.
She later then infiltrated the Oakton militia compound, where she learned that the whole extermination operation is being run by a man named Silvers, and continues to fend off the men in black until she learns from two of the locals, Uriah and Peter, where the satellite data disc is and where ATF agent Kelly is being held. She overheard Silvers talking about the location of the data disc and placed a tracking device on him, eventually learning of the disc's location with logan. She proceeded into the Militia Bunker where she meets Dusty Oakton, who leads her through the tunnel complex and into the bunkers, where she fights off the last of the threatening NSA men and helps the pregnant Mrs. Oakton and Dusty escape with the help of Logan.