No Way Out — Franklin W. Dixon

A Haunted Maze Has Twice The Dead Ends.
Frank and Joe are thrilled to be taking part in the grand opening celebration of a new maze in Cape Breton, Nova Scotia. By solving puzzles -- their specialty -- they could win a valuable prize! But once they arrive, the teens soon have a new puzzle to solve:
The owner and designer of the maze, Chezleigh Alan Horton, suddenly disappears.
As the boys make their way through a labyrinth of suspects, they face a new twist. Can Frank and Joe unravel a decade-old riddle to save the renowned mazemaster?