A hundred years ago, in the Himalayan peaks of Nanvi Dar, the daughter of an English earl is kidnapped by a huge hairy monster. In a secret valley Agatha Farlingham is introduced to a family of motherless yetis and devotes her life to their upbringing. She teaches them to speak, tells them stories and insists on polite manners. But as the decades pass, tourists come to the mountains, a hotel is built and yeti-hunters arrive. Agatha knows that there is one place in the world where they would be protected — her ancestral home at Farley Towers. When a boy and his sister stumble upon her hidden valley, she knows she has found the courageous people who will carry out her plan. The excited yetis are smuggled into the bridal suite at the hotel. A freezer lorry is waiting to put them into semi-hibernation on the long trip home. But the baby yak that has fallen in love with the youngest yeti foils the refrigeration plan and they set off on a hugely entertaining road trip half way…