The Secret of the Underground Room

by John Bellairs

Like Bellairs, Frumkes builds genuine dread through the collision of the mundane and the supernatural—here, a boy discovers his uncle's house contains an actual magical clock counting down to apocalypse. The pacing mirrors what makes Bellairs effective: slow-burn mystery punctuated by moments of real danger, with a young protagonist who has to think his way through supernatural threats rather than overpower them.

by Neil Gaiman

Gaiman does what Bellairs does—makes the supernatural feel like it operates by its own internal logic—but he stretches it across a full childhood. A boy raised by ghosts in a graveyard faces a very real threat from the living world. You'll recognize that same balance of whimsy and genuine menace, where the stakes feel concrete even when dealing with the impossible.

by Clifford D. Simak

Here's your genre curveball: it's science fiction, not fantasy, but it has that same wry, intellectual humor Bellairs brings to his supernatural mysteries. A man wakes up in a future where goblins, elves, and other creatures are real—preserved in a reservation—and he has to navigate a mystery involving them. The tone is lighter than Bellairs, but the puzzle-box plotting and the way it treats magical beings as real problems to solve will feel familiar.

by Gaston Leroux

A century older than Bellairs, but Leroux pioneered exactly what Bellairs perfected: a mystery where the supernatural threat turns out to be rooted in human obsession and tragedy. The phantom's possession of the opera house works like Masterman's possession of Father Higgins—an invisible force reshaping reality. The gothic atmosphere and the slow revelation of what's actually happening will feel like coming home to the source material.

by Barbara Taylor

Two young girls in Victorian London solve a mystery involving a ghost and uncover something far more sinister about the adults around them. Stratford captures that Bellairs quality of children taking the supernatural seriously while adults dismiss them, and the way the investigation pulls back layers to reveal something genuinely unsettling. It's got the same page-turning momentum and the satisfaction of a puzzle that actually holds together.