The Tuck family is confronted with an agonizing situation when they discover that a ten-year-old girl and a malicious stranger now share their secret about a spring whose water prevents one from ever growing any older.

Hardly a day passes without Trille and Lena inventing some kind of adventure that often ends in trouble. Whether it's coaxing a cow onto a boat or sledding down the steepest and iciest hill with a chicken, there is always a thrill--and sometimes an injury--to be had. Trille loves to share everything with Lena, even Auntie Granny's waffles ...

Eight-year-old Jack and his younger sister Annie use the magic treehouse to travel back to the Middle Ages, where they explore a castle and are helped by a mysterious knight.