Anthony Monday

When Miss Eells gives young Anthony a job at the library, he thinks he’ll just be dusting shelves and filing books. Instead, he discovers a hidden clue leading to the treasure of eccentric millionaire Alpheus Winterborn. Miss Eells thinks the clues are a practical joke left by the odd, old Winterborn before he died. But then why do things suddenly start getting so strange? And terrifying?

When Anthony Monday and Miss Eells find J. K. Borkman's diary, they think it contains the ravings of a lunatic. But soon violent hailstorms and blizzards rage across the land, and they must accept the frightening words: Borkman's son, carrying on his father's work, intends to turn into an icy wasteland. As the final blizzard explodes, they confront the evil Anders Borkman deep inside his father's tomb. How can they defeat such a formidable enemy -- and is there still time? -- Synopsis from Bellairsia.com

Anthony Monday can't understand why his best friend Miss Eells, the town librarian, is so excited about an old Dutch oil lamp, but she buys it anyway. Little do they know that the lamp was stolen from an underground tomb--a frightening place where eerie occult rituals used to be held. When Anthony borrows the lamp for a school science project, he makes a very big mistake: he lights it. Monstrous forces are at once unleashed, forces so demonically powerful that they threaten to take over the entire world--unless Anthony and Miss Eells can stop them! -- From back cover of Bantam-Skylark edition, 1989

While spending the summer in an old house on a desolate Canadian island, Anthony Monday and Miss Eells discover a chest that can transport them to another world and a maniacal group who are plotting the destruction of people on Earth.