The book I read was Found by Margaret Peterson Haddix. This book is 314 pages long. If you like books that are mysterious and adventurous then you will enjoy this book.
Imagine having a normal life, other than being adopted, but then one day you receive a letter that ominously says “YOU ARE ONE OF THE MISSING”. This exact thing happens to a boy named Jonah. This also happens to his friend Chip who, coincidentally, is also adopted. Jonah’s sister Katherine decides that she would help in this investigation. Together Jonah, Katherine, and Chip uncover a list. One side says witnesses. Another side says survivors. They attempt to clue all of these things together. Will they discover where they are really from, or be left in the dark? Find out in Found.