The Armies of Daylight
I stuck with Barbara Hambly's Darwath trilogy out of love for the author, only to find an ending that made three books of struggle feel pointless. Flat protagonists, frustrating plotting, and one of the most unsatisfying finales I've ever read.
House of Illusion
A young librarian visits her eccentric aunt's mysterious estate, hoping for adventure. An intriguing opening, a charming mechanic, and some genuinely terrible plotting make for a deeply disappointing Gothic mystery.
The Walls of Air
Rudy and Ingold undertake a perilous journey while Gil and Minalde investigate an ancient keep. Intriguing mysteries and stronger characterization can't quite overcome frustrating plot contrivances, questionable decisions, and a truly baffling approach to food storage.