She is a friend of Beth and Marlena and the girlfriend of Jason. In the film, she suggested to Jason that they should throw a farewell party for his brother, Rob, before his departure to Japan to accept a new job. Lily also invited Beth, which made Rob angry, leading to his argument with Beth. After the monster's decapitation of the Statue of Liberty, she — along with Rob, Jason, Marlena, and Hud — retreats to the Brooklyn Bridge, upon which Jason was killed by a swipe of the monster's tail. Upon retreating to the subway, she grieves about her boyfriend with Rob. While walking in the subway's tunnels, the group runs afoul of the monster's parasites; they barely escape with their lives, and Marlena ends up severely bitten. Shortly, after arriving in a field hospital outside the tunnels, she bears witness to Marlena's death. While shaken up by Marlena's death, she and Rob and Hud push on to rescue Beth, which they accomplish while catching the monster battling the US army in the distance. Later, the group finally arrives at the final extraction point for civilians. Lily is put on a different helicopter from the rest of the group, but her overall fate is left unknown.