Used book – Yannis (U4 #3), Florence Hinckel

Yannis lives in Marseille. His parents and little sister are dead. Now he sees their ghosts everywhere—maybe he's going crazy? When he leaves his house, terrified, his dog Happy by his side, he discovers a city overrun by rats and seagulls, and by young people ready to kill anyone who isn't part of their gang. Yannis hides, manages to escape patrols, to eat...

But no sooner has he reunited with his best friend than the latter is killed before his eyes. He then decides to flee Marseille and cling to his last hope: an appointment in Paris...