Professor David Wells (Hal Linden) is writing in his diary about feeling frightened and not knowing what to do about his worsening spells and increasing weakness. He remarks that Pendergast is dead and no-one can help him when he suddenly gets twitchy, drops his pen and furrows his brow.
"I guess some people take longer to heal than others."
The campus security officer, Chief Huston, is meeting with campus staff and asking for volunteers to patrol the quad and cemetery at night to prevent another murder by making sure there aren't any co-eds out alone. Apparently the police aren't getting anywhere and have other problems that are worse than college girls being murdered. Wells and his buddy, Frank Simmons (Mike Farrell), have decided to volunteer to go out and patrol.
Meanwhile, Laura Benton lets herself in to Wells' pad and starts poking around when Simmons shows up and also lets himself in. David should really lock his door. Laura says her folks own the house, but that she decided to come visit while they're away. She explains that it used to be her playroom and she wanted to check it out. She remarks on the photo of David and his wife, and Frank explains that David's wife died a couple years prior.
David comes home with a copy of Pendergast's manuscript and tells Frank he doesn't feel up to going out for drinks, so he cozies up with the manuscript instead. He reads that Pendergast believed the desire for human blood was a biological need caused by a chemical imbalance and was studying the relationship between vampires and blood diseases.
Frank catches up to David on campus and notes that he's not looking well. David shares that he's been working on Pendergast's manuscript about vampires. They head into their patrol meeting, which is crashed by Detective Thorpe, who tells them they are not trained for the patrols and need to stop since the police booked the dead girl's boyfriend for her murder. As soon as he leaves, Chief Huston suggests they continue patrols in case the police arrested the wrong person.
Frank's out patrolling the cemetery and starts chasing after Fern, one of David's students, to warn her to keep her eyes open. He sees a suspicious male wandering the cemetery and runs after him, but the figure disappears. David is on his way home and Laura intercepts him and starts putting the moves on him. It's an awkward moment. She gives him a peck on the cheek and leaves, then David goes home and receives a call from Frank, who believes that the person he saw in the cemetery was Pendergast. David goes to his desk, unlocks his drawer and starts writing in his journal about whether or not he may have murdered someone and that he's got to keep studying Pendergast's manuscript.
Frank and David are in Chief Huston's office to discuss Fern's murder, and the possibility that Frank may have seen Pendergast. They tell how Pendergast had been writing about blood diseases and vampires, and Huston lets them know that the girls all bled to death and had marks on their throats.
David is out patrolling and Laura emerges from the bushes. He asks what she's doing there and she says she just wanted to be with him, that she's not asking anything of him, she's just content to be with him. He confides that it's not just his deceased wife, but that he's shy with people he cares about. Chief Huston interrupts their interlude by screaming Wells' name and then apologizing for startling them.
David is at home reading the manuscript and realizing that he may have become something monstrous and there's no hope for him. While he wants to destroy himself, his desire for survival won't allow him to. Those darn college girls keep walking alone in the cemetery and Wells is there to chase Fern's roomie, Dana, and take a big sip of her vital fluids. Chief Huston spots him, but believes it's Pendergast. He fires a shot, but the perp gets away.
Chief Huston and Lt. Thorpe talk about working together to solve the crimes, but when Huston chooses to mention the possibility of a vampire, Thorpe decides to join him in a drink. Huston relates that he believes he saw Pendergast and shot at him the night before.
David and Laura are enjoying a candlelit meal she made for him in his apartment when Frank calls and David tells her he has to leave.
Frank and David meet Chief Huston at the cemetery, who hands them shovels and tells them they need to dig up Pendergast's grave. He has also brought along a handy stake like a vampire killing pro.
Frank and David are double dating with the gals for a picnic on campus, and the girls are concerned that the guys aren't eating. Lt. Thorpe breaks in and talks to the guys about Pendergast. He thinks that it would be clever if the real murderer used Pendergast to remove suspicion, and he suggests that Huston is the one responsible. Apparently he was accused of assault by a co-ed on another campus.
David is journaling about how he can't allow them to blame Huston and how he's afraid to love Laura. He gets the twitchy fingers and we next see her heading over to his place. He grabs her and makes the googly eyes and she screams. She crumples and he runs off. Frank drives up and finds her passed out. David is worried he's killed again and we hear Frank carrying Laura up to his pad, who doesn't suspect that he was the one mauling her.
Lt. Thorpe tells David that there are no leads in the attack on Laura. Thorpe says he questioned Huston, who was at the movies, but still thinks it was Huston. Laura and David return from a date and she asks if he has a dark side that he keeps hidden, but he denies it until he gets the twitchy fingers and exits the car, telling her to lock the door. He runs off to have the bulgy eyes and shaky hands in private, and Laura decides to get out of the car and go for a walk alone. She sees a shadow coming toward her and screams and runs into the arms of Thorpe. They hear a shot and Huston stands over David's body. As David lays dying, he asks Laura to promise to get his diary in his desk and burn it. He is grateful that it's over. Or is it?
We next see Laura reading the manuscript and she takes the diary from his desk and begins reading. Frank and Marne walk in and she puts the diary in the fire and says she wants to be with David on the train. It's a stormy night with lighting and thunder, and while on the train, she goes to the cargo hold to his casket, which opens and he rises up out of it.
If any of the co-eds had chosen to walk home with a friend, this would have been a short and uneventful movie. That's how horror movies can be educational. This tale had potential with the idea that vampirism could be a disease with possible treatment, but that idea never went anywhere. It's hard to feel any sympathy for David because his character ends up being pretty superficial. How is it that Laura didn't realize he would need a stake to the chest cavity after she had read his diary? She may have been confused by the fact that he ate meals and traipsed around in sunshine. I suspect he would tolerate the cross well enough too. You never know what part of the vampire mythology will be adhered to in a given story. It's not a bad episode and fun to see Hal Linden (a few years before he would grow a mustache and become Barney Miller) make big bug eyes and look hungry for blood, while Mike Farrell (a few years before M*A*S*H) gives forced laughs and is devoid of much expression throughout the show.