A series of murders -identical in technique- occur on the third day of consecutive months, and in three equidistant locations. "Simmetry in time... symmetry in place". The only clue, a cryptic religious message. The brillant detective, Erik Lonnrot, a "pure reasoner" with "something of the adventurer in him, and even a little of the gambler" unwittingly pits himself against his sworn enemy, Red Scharlach, who has fabricated the perfect trap for the little private investigator...