Tough-O-Meter

We've got your back. With the Tough-O-Meter, you'll know whether to bring extra layers or Swiss army knives as you summit the literary mountain. (10 = Toughest)

(3) Base Camp

The Angel Experiment may be a lengthy book, but the language is simple and clear—even when the plot gets a little convoluted and action-packed. As long as you can wrap your mind around the very cool idea of human-animal hybrids, you should pretty much be good to go for this one. And if you like exciting twists and turns, then fasten your seatbelt, because this ride is for you.