After receiving a mysterious message, Niko takes a new route to school and discovers a house he's never seen before. By solving a puzzle he is able to enter what turns out to be a strange place where universes are born. There's a cat that appears and disappears, and it has teleporters. The Door With Three Locks is the first novel to explain Quantum Physics—in a fun, comprehensible form—to the youngest readers, a Quantum adventure that 25,000 readers of all ages have enjoyed.