September by Gabrielle Lord
On New Year's Eve, Callum Ormond is chased down the street by a crazed man with a deadly warning: They killed your father. They'll kill you. You must survive the next 365 days. Cal feels like a failure - it seems as if he's fighting everyone and getting nowhere. He needs his friends like never before. Nobody knows the answer to the riddle, but Cal begins to understand that the mystery may be far bigger than anyone realises. He can't give up now, no matter what the cost.