 In a collision the Enterprise picks up a damaged probe, which identifies itself as Nomad, the name of an earth-launched exploration probe, but declares it has the mission to sterilize imperfect biological units, which seems to refer to all imperfect life forms. Fortunately it calls captain Kirk the Creator, referring to Nomad s creator Roy Kirk, and obeys him. A Vulcan mind probe reveals it has collided with a very powerful alien probe, meant to take and sterilize earth samples, and has fused with it to repair itself with damaged memory banks. It demonstrates its power to kill, but also to repair even a dead body, and to reprogram the matter-antimatter system 57% more efficiently. Then it appears to have scanned its origin is on earth, sets course but would find it  infested  with imperfect life...