How do I love thee? Let me count the ways.
Half Magic Mark, Katherine, Jane, and Martha discover a magic coin which only grants half wishes - the children end up half invisible (and rather ghost-like) and half on a desert island (which is, of course, just a desert), and have many more adventures with the magic coin.
Magic by the Lake On vacation, those same four children find themselves with an entire lake full of magic, which they must tame and learn how to handle in order to find the treasure that waits for them.
Knight's Castle Cousins Roger, Ann, Eliza, and Jack have an extraordinary summer when, after an old toy soldier comes to life, they find themselves transported back to the days of Robin and Ivanhoe.
Time Garden Those same four cousins spend a summer in a house by the sea and discover a magic thyme garden from which they embark on a number of adventures back and forth through time.
Eager began writing children's stories when searching for books to read to his young son. Enough said. Or maybe not--in each book he carefully acknowledges his indebtedness to E. Nesbit, whom he considered the best children's writer of all time--"so that any child who likes my books and doesn't know hers may be led back to the master of us all." Now enough said.