Rick Riordan Presents City of the Plague God (The Adventures of Sik Aziz, Bk. 1)

Thirteen-year-old Sik wants a simple life going to school and helping at his parents' deli in the evenings. But all that is blown to smithereens when Nergal comes looking for him, thinking that Sik holds the secret to eternal life. Turns out Sik is immortal but doesn't know it, and that's about to get him and the entire city into deep, deep trouble. Sik's not in this alone. He's got Belet, the adopted daughter of Ishtar, the goddess of love and war, on his side, and a former hero named Gilgamesh, who has taken up gardening in Central Park. Now all they have to do is retrieve the Flower of Immortality to save Manhattan from being wiped out by disease. To succeed, they'll have to conquer sly demons, treacherous gods, and their own darkest nightmares.