Peter's dog Nell has an amazing sense of smell. Whether it's finding a lost shoe or discovering who did a poo on the new gravel path, her ever-sniffing nose is always hard at work. But Nell has other talents too. Every Monday she goes to school with Peter and listens to children read. So who better to have on hand when they arrive one morning to discover that the school's books have all disappeared! Who could have taken them? And why? There's only one dog for the job... and Detective Dog Nell is ready to sniff out the culprit!