The Vanishing Game - Kate Kae Myers

The bond between twins is unmistakable. For Jocelyn and Jack, that bond was all they had. But now Jack is dead. Then Jocelyn receives a letter from Jason December-the code name Jack used when they were children. Only one other person knows about Jason December: Noah, Jocelyn's childhood crush. But Noah isn't the one contacting Jocelyn. Together they decide to return to Seale House, the frightening foster home where all three of them lived together. Seal House has more secrets than they could have ever imagined. And it suddenly seems possible that Jack faked his death, that the letter and the riddles that follow are cryptic clues leading to his real whereabouts. But someone else is looking for him-someone dangerous. Jocelyn and Noah must race to find Jason December. That is, if he's alive.