Lexa, with Shalimar following, is on the trail of her brother Leo and catches up to his New Mutant girlfriend Candace . . . just as she is killed. Brennan talks his way into helping her and passes info on to Shalimar and Jesse. It turns out Candace was dissected and her liver removed. Lexa and Brennan get a lead on the real killer, who works for an organ-legging ring run by an ex-GSA agent, Carter, while the others figure out Leo is a mentally unstable mutant, a Molecular, who can shift bodies and personalities at will, and earlier ended up in an institute run by Eckhart, on Lexa's unwitting insistence.
Lexa almost catches up to Leo but loses him but gets a tracker dart in him – they figure out that Leo's mutation makes him the ultimate compatible donor and thus a prime target for the organ-leggers. Carter locks into the signal while Mutant X figures out Leo has a violent "alter," Troy. Leo transforms into Tony, gets rid of the tracker, and attacks his pursuers. Troy goes after Carter and Lexa follows on her own, confronting Carter. The two of them were involved when they were in the GSA and Carter reveals he needs Leo/Troy's heart to save himself. The other Mutant X members catch up and Jesse and Shalimar leave carter to die while Troy takes down Brennan – Lexa is forced to kill him and Troy reverts back to Leo before dying.
(Copyright 2004 Steve Crow)