When my editor placed a copy of the second book in the Gustav Gloom series in my hands, I may have squeaked a little bit in excitement.

But honestly – I read Adam-Troy Castro’s Gustav Gloom and the People Taker nearly a year ago, and it was the most excited I’d been about a quirky, creepy middle-grade series since A Series of Unfortunate Events. There’s pretty much nothing not to love about a mansion filled with endlessly spooky rooms, shadows with minds (and appetites) of their own, and sweet characters with dark secrets.

And the covers. The covers. I mean, just…look.

Gustav Gloom and the People TakerGustav Gloom and the Nightmare Vault

Even better, each chapter includes another one of Kristen Margiotta’s gorgeous full-page illustrations.

In The Nightmare Vault, Castro does a brilliant job of answering some questions about Gustav’s mysterious past, yet creating many, many more. Gustav and Fernie have a new enemy – a shadow eater, who is determined to find the Nightmare Vault in the Gloom mansion. And he is…creepy. Very, very creepy.

Even sunshine is creepy in this book.

What I loved best, though, was how Castro offered explanations for certain elements of Gustav’s home – and of Gustav himself – that were realistic and believable, yet still magical. That’s a tough line to find, and he nailed it. And by the end, I loved Gustav even more than I did when I finished the first book. Same goes for his relationship with Fernie, which is as genuine and touching as any I’ve ever read.

Gustav Gloom and the Nightmare Vault will be in stores April 2013. If you like dark stories with a touch of sweetness, this is a series you’ll adore.