The triangle mystery

A man is brutally murdered in a dark alley of the oldest part of Perpignan, a
sleepy town of Southern France near the Spanish border. He has the bloody mark
of a triangle, carved on his cheek, a symbol that intrigues the police
especially young Dominique d’Astié, recently promoted Lieutenant on the force.
A mysterious coded note and a brochure about the Holy Thorns of Christ are
found in the victim’s pockets. These clues lead the criminal investigation on
an esoteric trail, which will involve Freemasons and other secret
Brotherhoods.