Twins Charlie and Helen are totally dismayed when their family trip to the zoo - already sounding lame - actually turns out to be a visit to a petting zoo, filled with boring farm animals. After an accident in one of the enclosures, the twins become instrumental in the farm's alpaca herd running amok, with owner Farmer Phil determined to bring both the alpacas and the twins to heel. Fast-moving and funny, with weird insights shared into alpaca behaviour (pronking, anyone?!), this is an enjoyable read, and not too long or overwhelming for reluctant readers.