Rebecca Stead, Newbery Medal-winning author of When You Reach Me, said this book is "brimming with surprises and grand adventure. Brave, smart, and full of heart, Madeline and Ruby are a gust of fresh air."    Mad's dad is the Bird Guy. He'll go anywhere to study birds. So when he's offered a bird-tracking job in Central America, his bags are packed and he's jungle bound.   But going bird tracking in the jungle and disappearing completely are very different things, and when the Very Strange and Incredibly Creepy Letter arrives, Mad can't shake the terrible feeling that her father is in trouble.   Roo, Mad's younger sister, is convinced that the letter is a coded message. And their mom is worried, because the letter doesn't sound like Dad at all.
