Zed hires a new alien field agent, infuriating Elle who's been bucking for a promotion to the field for months. She proposes a replacement for herself in the lab; Dr. Zeeltor, a wacky eccentric genius, whom Zed knows by reputation. Zed agrees to give it a try and promotes Elle, but she's mortified to discover her new partner is Agent X. Meanwhile, Jay is having minor aches and pains, thinking nothing of it not realizing he's got a life threatening neuro-spinal disorder resulting from exposure to a thistly alien called a Bovus. He refuses to let the new Dr. Zeeltor examine him. Things come to a head after X puts Elle's life at risk and Zeeltor operates on Jay without his permission. They both go rant and rave to Zed, insisting he fire his two new MiBs. But it's not to be. Zeeltor and X are now part of the team for good.