The Boy Next Door: "The three main characterizations are a little thin. The story starts with Betty waiting for her brother Robin to return home from boarding school, and since her cousin Lucy is also due to arrive the same day, Betty is excited at finally having someone to play with! In the usual Blyton fashion, ages are quickly established, in this case with Betty thinking to herself, 'Robin's eleven, Lucy is ten, and I am nine.' Both Betty and Lucy are almost like hangers-on, not integral to the plot in any way. Robin starts out being a bit of a snot, by shunning Betty's enthusiasm to see him and announcing that 'it will be dull with only two girls to play with.' Robin warms to Lucy when he sees she's brought her dog Sandy (after all, a Blyton book wouldn't be complete without a pet of some kind—although the Secret series managed quite well without any regular pets at all)."
The Treasure Hunters: "When Jeffery, Susan and John are told that their mother and father are going away for a few weeks, because their mother is feeling under the weather and needs some 'strong sea-air,' the children find themselves shipped off to Granny and Granpa's. But it's all good news. Jeffery, the eldest of the three children, remembers the old house well—he says it's the sort of place all kinds of things have happened, and 'anything might still happen.' Susan has been there too, but hardly remembers it, while John, the youngest, has never been there at all. And so, with very little fuss, the children are packed up and ready to go."
The Treasure Hunters by Enid Blyton: "The story begins with news that Jeffrey, Susan and John are going to stay at their Granny's and Grandpa's home, Greylings Manor, as their parents were going away to the sea-side, so that Mummy could get some 'strong sea air', recommended by the doctor."