Since the mercenaries are fighting Trigen

Jack has little trouble climbing up the slope of the volcano to the headquarters
Kriegel has apparently discovered a method used to stop the eruption and use the flow of lava to generate electricity. Jack asks Kriegel who has mutated after being injured for an antidote. Kriegel states that there is no time to prepare the serum and that Jack will be a specimen in an hour not to mention Valerie. Then Doyle appears nearby implying that there is still a remaining serum. Deciding that he will not leave the island until Doyle has found the antidote Jack takes a weakened Valerie to the docks and then he returns to the factory.