Sil 's violent outbursts during sleep make the scientists consider her a threat . They try to kill her using cyanide gas but she break out of her containment cell and escapes . The government assemble a team composed of anthropologist Dr. Stephen Arden ( Alfred Molina ) , molecular biologist Dr. Laura Baker ( Marg Helgenberger ) , " empath " Dan Smithson ( Forest Whitaker ) and mercenary Preston " Press " Lennox ( Michael Madsen ) to track and destroy Sil . Sil mature rapidly into an adult ( Natasha Henstridge ) in her early twenties and make her way to Los Angeles . Her body strength , regenerative ability and intelligence make tracking her extremely difficult . The scientists fear she may mate with human males and produce offspring that could eliminate the human race . Sil is intent on producing offspring as soon as possible , and kill several people to prevent them from notifying the authorities or simply to use their clothing .