When Brennan is dealing with the Underground, one of its sub-leaders, Rick, comes down with a disease that causes his powers to flare out of control. While Brennan is confined with the remaining underground members, Adam and the others take Rick into isolation and try to find a cure. Word comes in of other mutants suffering from the plague, and while trying to help one of them, Adam and Shalimar meet Charles Marlowe, a mutant with the power of invulnerability. They and Eckhart make a deal to work together to cure the plague, which Marlowe isn't too happy with. Obsessed with death, Marlowe hangs around the dying mutants trying to see what they see at the moment of death. Jesse and Emma are accidentally infected by the dying Rick and go into comas as well. Adam figures out that Marlowe's invulnerability is supra-rapid cell regeneration, and extract his unique DNA to implement a cure. This makes Marlowe "vulnerable" again. They need Eckhart's computer system which only a grateful Marlowe can gain them access to. Marlowe tries to hold off Eckhart by bluffing, but Mason sees through it and Marlowe is killed. The remaining mutants are cured