While Mrs North, Marvin's teacher, is on holiday she asks him to look after Waldo - her dog. Suddenly, Marvin has become the luckiest boy in school. He'll get to sniff about Mrs North's house, look in her wardrobe, check out her bathroom and rummage in her fridge ...Well that's what Stuart and Nick, his best friends, would like to do. But Marvin takes things a little more seriously. After all, he gets paid $3 a day and he will get a bonus on top if everything goes smoothly. What could possibly go wrong? Just how long can Marvin hold on to his luck...Louis Sachar tells this tale with a refreshing and bold frankness and again the characters are vividly portrayed in this the fourth of the series.