The novel is set in a small-town in rural Texas. It's Friday evening, and a giant drive-in movie theater called The Orbit is playing six movies as part of its “The All-Night Horror Show”. Protagonist Jack, who presents the story in first-person, is with a sort of “losers club” that shows up for the night's festivities. But, somewhere in the middle of movies like Texas Chainsaw Massacre and The Toolbox Murders, a weird anomaly – call it a comet or alien spacecraft – swoops down and literally covers everything surrounding the drive-in parking lot with a weird flesh-eating black goop. In essence, it is sort of like a slimy alien fence containing just the drive-in theater. Everything else is just lost in the blackness.
Like most survival horror novels (many which borrow from this very book), the book descends into a fight for survival as the theater's audience find themselves cut-off from civilization. With only a concession stand for food – free popcorn and soda while supplies last – and a lone bathroom, needless to say that humanity quickly shows it's darker self. As the days go on, mob violence takes control with rapes, beatings, shootings (it is Texas), and various factions forming. Jack sides with The Christians until he realizes they have a secret, savage way of surviving the violence. But, things get even more bizarre, deadly, and insane when Jack's two friends become struck by some sort of alien lightning that turns them into demonic cannibals that can do some really far-out stuff.
The Drive-In is a horrific fantasy with science-fiction elements that bring to mind all of the B-movie black and white classics from the mid-20th century. That's the idea, and Lansdale absolutely nails it. His combination of humor – unintentional or not – sets a framework for these characters to behave in outrageous ways. Aside from the sky-level fun, one could read some subtext about the drive-in movie theater disappearing by the late 80s, replaced by shopping mall caverns and standalone brick-and-mortars that didn't exude the same sort of late night, backseat enjoyment. Additionally, it could show the sharp contrast of the old B-movies compared to the graphic, more mature movies that were being released in the grindhouse 70s and 80s formula. Sort of an invasion from nowhere of a barbaric savagery that far surpassed the practical “safe” effects of black and white Hollywood.
Two more books in the Drive-In series were published, The Drive-In 2: Not Just One of Them Sequels (1989) and The Drive-In: The Bus Tour. Additionally, all three books are published as an omnibus titled The Complete Drive-In.