** spoiler alert ** This book is the last book in the 39 Clues series. Towards the end of the book, Isabel ties all of the people who Amy, Dan, Jonah, Sinead and the other people of the other branches love. In the end, the clues added together are ingredients to make the Cahill serum which makes them the strongest person alive. But while Isabel mixed the serum ingredients together, everyine leaped forwards to stop her from drinking it. Eventually, Dan gets targeted by Isabel nd gets hurt by her. Amy being protective of her little brother grabbed whatever her hands laids on: the serum and smashed it as hard as she could onto Isabel's head. Then Alistair, gave Isabel the pill to make her forget everything that happened and to knock her out. He would also bring Isabel to court and sue her for murdering Amy and Dan's parents locking her up in jail for the rest of her life.