The Egyptian cross mystery / Ellery Queen ; introduction by Otto Penzler.

Enhanced descriptions from Syndetics:

Ellery Queen investigates a series of bizarre murders that lead to a mysterious religious cult

"Crucifixion on Christmas Day." That's what the newspapers report when a small-town schoolteacher is discovered dead, beheaded, and tied to a T-shaped cross on December 25th. It's a murder bizarre enough to pique Ellery Queen's interest -- and intriguing enough to lure him to the West Virginia village where it occurred to take a closer look. But when he arrives, Queen is met with too few clues and too little evidence to produce a satisfactory verdict, even for a master sleuth such as himself, and so returns home to New York defeated.

The yuletide gore is a distant memory when the next such murder occurs, identical in every way, but now the location has moved to Long Island. When Ellery Queen learns that the sun-worshipping nudist cult he encountered down south has made the same relocation, it becomes clear that the group and the killings must be intertwined. But then several more crucifixion murders follow, drawing Queen deeper into a tangled and eerie puzzle unlike anything he's encountered before. It will take all of his powers of deduction to uncover the killer.

Reissued for the first time in decades, The Egyptian Cross Mystery is a "fair play" puzzle in which the readers have all the clues necessary to solve the mystery themselves. It is the fifth of Ellery Queen's cases, which may be enjoyed in any order.