Both book four. Hardcover, 39 clues Double cross ,Mission atomic, Checkmate 13-year-old Dan Cahill and his older sister Amy are running out of time. and Excel k l known as outkast is already recreated three of history's worst disasters and his save the worst for the last. if Dan and Amy can't find and stop and the outcast fast he will initiated a full-scale nuclear meltdown. but as Dan and Amy raced around the world they discovered something horrifying. the outcast disasters are only a smoke screen to cover up his true plan a diabotical revenge on the family that betrayed him. Sue and Amy and Dan have to confront a hard truth sometimes the only way to save the world is to sacrifice everything you love. & book four Sisters of isis The haunting by Lynne Ewing city is still struggling with her newfound powers. well Mary and Darla continue to learn new spells suti can't seem to master even the most basic of her magical gifts. and she may be running out of time. someone or something is haunting sweetie. but frustrated by her feeler to keep up with the other descendants and distracted by the mysterious new boy at school sooty is more vulnerable than ever. she's got the strength of the other sisters on her side but will that be enough?