After the Eve incident that took place in New York, Aya Brea, formerly a member of the New York Police Department, is relocated to Los Angles in order to put the past behind her. Accepting a position in the FBI's Mitochondrion Investigation and Suppression Team (MIST), Aya put her unique talents to use fightning the mitochondrion meance wherever it appeared. Three years after the initial event, it seemed that the threat had finally dissipated...until now.

A distress call from a major metropolitan area followed by the destrucion of the responding SWAT team and police helicaptor signaled the emergence of a new breed of the mitochondrion threat. Dubbed Neo Mitochondrion Creatures (NMC), these new monsterst seemed to have evolved beyond anything Aya has encountered. It is now a race against time to uncover the origins of these creatures before the infestation spreads any further, Aya will travel far and wide trying to stay one step ahead, all the while fighting off both monsters and a conspiracy that seeks to replace humans as the dominant species on Earth.