Every afternoon, the sly cat Kokkinis takes his place on the bougainvillea pot, hoping for a treat, as tour groups walk past him along the cobbled path on their way to the island’s historic bastion.“You traitor,” Mr. Takis calls him — the man in the faded white tank top from the 1980s, who longs for the days when he and his partner, Chara — back when she was still flesh and breath, before she became stardust in the vast universe and her jasmine withered — would bring out their canvas chairs to watch the sunset from that very same spot now trampled by tourists.Then, during a chess match with his grandson, the boy shares with Mr. Takis an old island legend he heard at the Chess Club.And that’s when everything starts…