Flat, stylized illustrations and a meandering yet linear plot proclaim Boyle’s background in animation (he’s the creator of Nick Jr.’s Wow! Wow! Wubbzy!). Hugo is a purple hippopotamus with a huge head and small, blocky body. Hugo, his dog, their home on a hill, the town below and its residents all have the deliberately retro charm of many contemporary cartoons. The characters (all animals) have thick, black outlines that appear to advantage on the sometimes busy compositions, which feature a mix of double-page spreads and vignettes of various sizes. The relatively subdued palette allows readers to easily follow the long, red string that propels the plot. This is essentially a one-joke book, though the long-ish text might suggest otherwise. The mysterious string that leads Hugo through the town and introduces him to a number of new friends turns out to be “a very long thread from his old underwear.” Tomorrow’s adventures are implied in the blue string that leads from Hugo’s rug to his bedroom window. Undemanding but potentially popular. (Picture book. 3-6)