 Two " containment ships " soon arrive , demanding access to Enterprise in order to stop the virus that killed millions of their people 60 years ago . Tucker refuses , but invites their leader , Tret , aboard . Tret explains that the original inhabitants of the planet , the <unk> <unk> , created the virus in an effort to continue their species . Believing it impossible to cure , he sends a team to the planet 's surface to neutralize Archer and Sato . Archer leads Sato and T 'Pol to <unk> , but they find it in ruins . Tucker then beams down with a team of MACOs and rescues them . Enterprise then warps away , but the alien ships pursue and attack the ship . Tucker asks Tret to allow Phlox more time to synthesize an antidote , but Tret refuses . Before he can board the ship , Phlox arrives with Archer and Sato — now mostly restored — and promises Tret a sample . Later , as Phlox plans to destroy the last vial of the virus , Archer tell him to keep it as a legacy of the now extinct species . 
