Janine Melnitz visits Metropolitan Hospital for a check-up and brings Slimer along. In the waiting room, a short-tempered Head Nurse repeatedly tells Slimer to be quiet as he leafs through a copy of Ghost Stories magazine. Outside, Professor Dweeb arrives in his van with a new gadget, the Ghost Detector, and enters the hospital with his robot companion Elizabeth. The Ghost Detector malfunctions and clamps onto Slimer's vacated chair with sharp metal teeth; the noise earns Dweeb an immediate ejection from the Head Nurse.
Slimer wanders the hospital in search of food and disturbs a patient in his room before finding himself in the maternity ward, where he calms the crying babies with a lullaby. When the Head Nurse returns for feeding time, Slimer disguises himself as an infant. He snatches a batch of baby bottles and belches loudly; the nurse attributes the commotion to overwork and leaves.
Dweeb sneaks back in disguised as a physician. Slimer rounds a corner and runs directly into him, and Dweeb improvises a fake physical examination while readying a Ghost Trap supplied by Elizabeth. The trap snaps back onto his own hand instead, sending Dweeb howling into an exam room. His fallback plan is to deploy a remote-controlled food cart as bait, but the Head Nurse discovers the cart first. Believing she is Slimer, Dweeb triggers the device, snaring her instead. The nurse destroys the remote control and the cart runs wild, carrying Dweeb and Elizabeth into a laundry chute. Slimer strolls back to the waiting room just as Janine's appointment ends, and the two leave the hospital together. In the episode's final beat, Dweeb vows that science will ultimately prevail, only to have Elizabeth bite his left hand.
Professor Dweeb is the recurring antagonist of the Slimer! segments. A bumbling scientist obsessed with capturing Slimer, he carries an array of gadgets and is assisted by a small robot named Elizabeth.
Elizabeth is Professor Dweeb's robot dog-like companion, used to supply and operate his various capture devices. She also bites her own master when his plans fall apart.
Head Nurse (Mrs. Stone) is a one-episode character who enforces strict quiet in the hospital waiting room and inadvertently becomes Dweeb's victim when he mistakes her for Slimer. Later in-production documentation gives her the name Mrs. Stone.
Dweeb brings several devices to the hospital in this episode:
Metropolitan Hospital is the primary setting. The episode moves through the public waiting room, a patient's room, the maternity ward, and the hospital corridors, with the climax running through all three areas before ending back at the waiting room.