The Beast Under the Wizard's Bridge - John Bellairs

When Lewis and his best friend Rose Rita set out to explore old Wilder Creek Bridge and the deserted farm nearby, they discover shocking secrets: the destruction of the bridge threatens to release a horrifying monster, the legacy of a long-dead evil magician. Even Lewis's Uncle Jonathan and the magical Mrs Zimmermann may not be able to vanquish this ferocious creature! For fans of Goosebumps.