Gwen’s older brother Ken is missing, and she asks for Ben and Kevin’s help to find him. The gang stumbles upon a Highbreed base in a small town called Santa Mira that manufactures Xenocytes, headcrab-style parasites that mutate humans into DNAliens. Ken has been infected by one of the Xenocytes, but Ben is able to remove it with the help of the Omnitrix. With Ken in tow, the gang finds Grandpa Max inside the base. While the team and Ken destroy shipments of Xenocytes, Max sets about destroying the factory while searching for the egg-laying machine. Upon their return, the gang finds Max locked in battle with a Highbreed commander. In an act of self-sacrifice, Max uses an unfocused Null Void projector to destroy the Highbreed base, seemingly killing himself and the Highbreed in the process.
