I thought this was a great comeback from the third book, which wasn't my favorite. The action level was high, and the villain was more than a worthy match for Artemis, Butler and Holly Short. There is a very intense and tragic moment that is the catalyst for what follows in this book. Holly thought she'd seen the last of Artemis, but when the chips fall down, she's rushing to save him and Butler and knows that he's the only one who can deal with the villain, the nefarious Opal Koboi.

The characteristic wry humor is here, but Colfer takes things seriously in many ways (no patronizing tone). Artemis might be fourteen, but he is a mature fourteen who doesn't view the world from the vantage point of a child. I was happy to see Butler in the action as much as Artemis, and their back and forth, and that of Artemis with Holly, is what makes these books so enjoyable.

Opal is a very evil villain, not troubled by any morals that would preclude murder or even feeding a boy to bloodthirsty trolls. What makes it even worse is she looks like a cute little girl. I was very happy to see her dealt with in a fitting manner by Artemis and Co.

This is a clever and enjoyable series that many younger readers and some older ones will enjoy.