Grin is a budding young pianist with a scientific curiosity that runs in the family. His father, a scientist, is under pressure at work since his boss Professor Musselmann went missing under mysterious circumstances. Meanwhile Grin is given to tormenting little insects - especially flies - in the cause of his own scientific research. In fact he has little time for anything else, and least of all for his sister Priscilla. Then one day he’s literally cut down to size by a fat disgruntled bluebottle.Dumped on a lily pad in the pond at the bottom of the garden, our sadly subtracted hero meets Frenchy the frog, who takes pity on Grin and carries him off on a subterranean journey through the depths of the pond to a strange and baffling world. Frenchy assures him that, if there’s an answer to be found anywhere to Grin’s problem and a way for him to get back to his normal size, then it’s here. But Grin finds that everything in this strange world is against him – even the grass steals his clothes! By a curious irony, it’s when he is thrown into slavery with the ants that Grin learns of the green cow and one of life’s last little secrets, which – if only he can find it – may just free him from his predicament. It is during his captivity with the ants that he unwittingly gets the first inkling of what might have happened to his father’s boss. After literally almost losing his head in the ants’ fiendish and macabre idea of entertainment, he eventually escapes his slavery to set out in search of the green cow. And on the way, he encounters a whole circus of bizarre animals and people. He is hounded at every move by a pair of strange law enforcement officers called Bananas and Peachface. He falls into the hands of 3 witchy old ladies with a collector’s passion for keeping little boys in jars. He carelessly loses his fine head of hair to Glatz, the uglier half of an exceptionally ugly pair of innkeepers. He almost suffocates in the sweet honey flavour of the night air. And finds shelter at last in a hotel run by General Keepemout, where the only other guests are gigantic earwigs, ladybirds, ants, and mole crickets. It proves an unappetising place in which to dine, but this strange hotel turns out to hold the most heartening clue Grin has yet found to his salvation.The next day, encouraged by his discovery, he continues on his quest to the distant mountains. It is a long and arduous journey that takes him through strange talking forests and across a “mistifying” desert. Yet journey’s end proves a disappointment at first. Grin sees no sign of cows anywhere, green or otherwise – just orchards upon orchards of rose trees. It is only when he meets Achilles, a kindly red ant, who introduces him to an oddball dairy farmer that he finds the green cow is not quite what he expected. Nor is the creature particularly eager to help Grin out of his dilemma.Yet even when he eventually gets the creature onside, Grin has yet to meet the strange and long since missing Professor Musselmann. And when he does, he finds he still has a number of obstacles and tense moments to overcome before he can get back where he belongs a much wiser lad than when he started out.