Diligence Peaslee notices that Harmon Creel’s yearbook photo didn’t come out; the chair is there, as is Harmon’s shadow, but he’s gone. The yearbook gang figure he might be a vampire, and head down to his locker, which contains a five-gallon plastic bag of river water with some live bluegills swimming in it. They then try the biology lab, of all places, to see if Harmon’s missed a lot of school lately or if the bluegills were stolen. While they’re looking around, a fire extinguisher clangs to the floor outside. Julie and Marcus rush to the door as one, colliding, and allowing the mystery prowler time to run around the corner. But his wet shoes leave prints on the clean floor, and all pursue him to the Quad, an intersection of the school’s four main halls.
The principal, a tall, thin man dressed all in black who speaks sternly and without emotion, makes an appointment to talk to Alexandra Harrow after she tries to stall him with talk of afterschool extra credit assignments. No one can remember the principal’s name. But they do find a fire extinguisher missing from its bracket, twisted off as if by incredible strength. A pair of wet size 14EEE sneakers are found hidden in the ceiling; apparently the mystery man ditched his wet shoes and proceeded on foot.
Dr. Armitage, faculty advisor, shows up and concludes that someone deliberately led our heroes away from the bio lab. They return and find the catfish from the specimen tank eaten, its bones in the trash can, and a set of blood-typing slides from 10th grade intro bio missing. Harmon is in that class.
With darkness approaching, Dr. Armitage warns that tonight is the first of three nights of St. Vigeous, the vampire saint – it’s sort of a Mardi Gras for vampires, and kidnappings are expected to rise as the vampires stock up for the festivities. The gang drive in Armitage’s car to the Ravine, a wilderness north of town, to look for vampires, Harmon Creel, or trouble.
They find two out of three – a flood of rats comes charging out of the brush, and when Alexandra sets them on fire with a spell, one of them turns out to be a vampire, shapeshifted into a rat! He attacks, and Diligence and Billy are trapped in the car while the vampire slithers underneath it. Meanwhile, another vampire grabs Marcus from behind, stunning him, and Julie rushes them both, tackling Marcus instead of the vampire because Marcus takes a sidestep to get the vamp himself. They go down together, the vampire attacks, and Julie and the vampire trade punches until she kicks him up in the air and over on his back, so she can stake him.
Meanwhile, the other vampire is crawling over the hood of the car, smashing the windshield. Billy Boucher puts the car in drive and bails out, so that it sails into the ravine and explodes with the vamp still clinging to the hood. Two other vampires run from the flames, howling.
While that was a good thing, it didn’t exactly solve the mystery, so the gang (minus Dr. Armitage, who goes to the Starry Wisdom church for some research, and to fill out insurance forms for the loss of his car) go look up Harmon’s home address, out on Ayelsbury Pike a ways outside town. They take Marcus’ sputtering pickup, the Green Hornet.
When they get there, the house is deserted, but there are lights and voices coming from the river on the other side of the house. Most of our heroes sneak toward the sounds silently; Marcus, however, does not, and alerts the Creels. Two of them, huge baldheaded Rick Creel (a senior at Darkwood) and white-bearded Ezikiah Creel, come around the house and run into Julie, who says she’s lost. She gets Rick to look at “her” car, to see what’s wrong with it, while Ezekiah grumbles and goes back around the house to the river. Diligence sees two dark shapes slipping through the woods, heading around back, and sneaks over there himself, discovering two vampires feasting on two of the Creel family, with Ezikiah face down in the river, apparently dead!
Alexandra attacks with a crowbar, Marcus with an ax, and Diligence with a set of bolt cutters. The male vampire holds his own until Rick Creel smashes him in the head with a lantern, knocking him into the water, and heads in after him. Meanwhile, the female vampire is trying to dominate Billy’s will, but he grabs up a scull (which is not the same as an oar, of course, though similar) and sets the cotton batting on its end afire! He drives the female vampire back to the end of a small dock, and when Julie and Rick join him, they face the vampire together. She grabs Diligence and uses him as a shield. She smiles, and suddenly Rick grabs Julie by the throat and starts to throttle her! Billy swings a lantern at Rick but hits Julie, the vampire slashes Julie’s arm with her razor-sharp fingernails, and the male vamp emerges from the water, hungry for blood!
But it could be worse. Diligence manages to distract the female vampire, who introduces herself as Alexandra, so that she releases Rick from her mental control, and he in turn releases Julie. The male vamp leaps right over Billy and Alex, landing inches behind Julie with his fangs agape, and WHAM! She stakes him. Oops.
Alexandra tries her mind powers on Julie, but isn’t getting anywhere, when the water behind her begins to bubble. As she brags about how many people’s blood she’s tasted, a dozen fish-frogs like misshapen hybrids of octopus and human emerge from the water, grab her, and drag her under, after which the water churns frantically for a minute before settling down.
Rick explains that today is Harmon’s birthday, and he’s being immersed in the river as part of the preparations for the Change, when he and his family of were-fish Deep Ones become fully amphibian. Harmon’s photo was washed out by an amulet the Creels all carry, which keeps people from noticing their pale, greenish skin, huge staring shark eyes, sharp teeth and wide mouths. Apparently it works on cameras, too.
The next day at school, Julie congratulates Harmon on his birthday. He says now that he’s 15, he can try out for the varsity swim team. With him and Rick both, they’ve got a good chance to be the best in the state … except for Innsmouth, of course.