Sandy and Fergus are moving to the country, but the whole family face difficulties they hadn't imagined. Their father is recovering from a heart attack, and Sandy and Fergus manage to offend the local children. But they do have a pony, something they've longed for all their lives. Mimosa is beautiful: a palomino Welsh cross, but she has a mind of her own, and neither Sandy nor Fergus know enough to stop her.

Published in the 1970s this series is a much more realistic one than Diana's earlier series of the 1940s and 1950s. Sandy stops eating beef when she becomes fond of the cattle her father keeps. She has very mixed feelings about hunting. There are people with difficult family backgrounds, and a thoroughly realistic outcome to the children's greatest adventure, when they try and stop rustlers stealing their animals.