When ten-year-old Cyrus sees a For Sale sign plunged into his front lawn, it's a complete and utter disaster. Usually, his younger brother, Rudy, is the scaredy-cat, but for the first time in his life, Cyrus is terrified. He's lived at 637 Petunia Boulevard since he came to live with his adoptive mom and dad at two months old. Won't he go hurtling into outer space without these four familiar walls to hold him in? Luckily, Cyrus has a few sneaky tricks up his sleeve to stop this moving business before it even gets started.