Used book – The Man with the Blue Circles, Fred Vargas

"Victor, evil spell, what are you doing outside?" For four months, this phrase has accompanied blue circles that appear at night, drawn in chalk on the sidewalks of Paris. In the center of these circles, imprisoned, is a piece of debris, a discarded item, a lost object: a paperclip, a candle, tweezers, a pigeon's leg... The phenomenon delights journalists and a few psychiatrists who theorize: a maniac, a gambler. Commissioner Adamsberg, however, isn't laughing. These circles and their heterogeneous contents are an ill omen. He knows it, he feels it: soon, the innocuous oddity will turn tragic. He's not wrong. One morning, the corpse of a woman with her throat slit is found in the middle of one of these blue circles.