I'm not sure who that ghoul on the left side of the cover is supposed to be - maybe a young Tommy Wiseau. But the fascinating cover is not the only reason I picked up The Boggart. It's because: Susan Cooper, scotland, boggart.
It's a lighthearted story with an emotional core (really!). The boggart in this story is not the same as the scary bloodsucking things in the Spook's Apprentice series. It is invisible, immortal, and eats ice cream with its tiny "hands". And when its master dies and a distant Canadian relative comes with his family to scope out/put the Castle Keep on the market, it accidentally gets stuck in a roll top desk and shipped to Canada.
Where, somehow, the magical properties of iron don't affect it as much, or maybe there's just not as much iron around as I'd assumed.
Anyway, things turn out okay and Susan Cooper is still magic even when she's not writing something really heavy.