She appeared at the beginning of the film carrying a cake in Lunar Max Prison. After getting through the security checkpoints, they brought her to Boris' cell where they french kissed for a few seconds to the disgust of the guards. But then Boris' plan went into action as Lilly brings out the Weasel, an insect-like pet of Boris', who then quickly kill much of the guards. After reuniting with the Weasel, Boris was quickly able to escape and kill the guards with Lilly close behind, and she got him armed with a large blaster stolen from the armory. They both reached a room full of guards, but Boris took the blaster and shot a hole in the roof with caused them all be sucked into space, but Lilly was caught in the suction and held on to Boris, who grabbed her with one arm. Boris then turned his dog-eat-dog methods on his own lover and said: "Sorry, darling. We did love the cake." and released her, causing her to be sucked into the vaccum of space with no trace of her body.
- In the credits of Men in Black III, Nicole Scherzinger is only credited as "Boris's Girlfriend".
- Since Boris was killed in the alternate timeline, this might mean that Lilly doesn't die in that timeline.