The darkest of the lovely Green Knowe series, this book is quite frightening, but ultimately an affirmation of the power of love and courage. It has stayed vividly with me over the years.

Another anomaly in the Green Knowe series: it's SCARY. If 'Stranger' had too little magic, 'Enemy' has too much of it: dark, spiteful, evil, black magic that nearly overcomes Mrs Oldknow, that takes everything that Tolly and Ping can throw at it, and that's even almost too strong for Green Knowe itself. In fact, forget scary – it's downright terrifying, and if I'd read it when I was a kid I would probably still be having nightmares. ( )

Well-written book; the author is, thankfully, not afraid to use big words and think about important things. There is an evil character in the story and kindness alone is not enough to defeat her; i.e., it is a disturbing story. ( )

Much darker than the previous books, this book sees Green Knowe threatened by great evil. The goodness innate in the house is not enough to fight it, Tolly and Ping and Mrs Oldknowe must call on all their strength and imagination to save the house and themselves. ( )

An Enemy at Green Knowe has a different feel from the other, innocent stories in the series. Because it deals with a witch who practices black magic and literally worships the devil, I would hesitate to recommend it for children. I found it quite disturbing; any sensible person would request a police restraining order on the woman who so manipulated and threatened, not to mention invaded the privacy of, the residents of Green Knowe. There is magic in this book - but much of that magic felt satanic to me, while in the other books it felt playful. Now, I’m sure someone out there is rolling their eyes at the thought of me taking this book so seriously, but I honestly felt this book had less innocence and playfulness than the others had; so much less that this book was disturbing to me while the others had not been.

Thoughts on the entire series on my blog