Hot summer of 1900. The World Exhibition is taking place in Paris. And in one of the neighborhoods, far from the noisy celebration, an unusual murder was committed: an arrow with red plumage ends the life of the Japanese sailor Isamu Watanabe, who had recently arrived in France. The murdered man clutches a strange note in his hand...Amateur detective Victor Legree promised his wife never to investigate again. But this time he and his faithful comrade Joseph Pinho will have to outdo themselves: after all, Victor’s adoptive father, Kenji Mori, is in mortal danger.