The stakes have risen even higher in this third book in the Hourglass series. The Hourglass is a secret organization focused on the study of manipulating time, and its members — many of them teenagers -have uncanny abilities to make time work for them in mysterious ways. Inherent in these powers is a responsibility to take great care, because altering one small moment can have devastating consequences for the past, present, and future. But some time travelers are not exactly honorable, and sometimes unsavory deals must be struck to maintain order. With the Infinityglass (central to understanding and harnessing the time gene) at large, the hunt is on to find it before someone else does. But the Hourglass has an advantage. Lily, who has the ability to locate anything lost, has determined that the Infinityglass isn't an object. It's a person. And the Hourglass must find him or her first. But where do you start searching for the very key to time when every second could be the last? (from Goodreads)
To catch you up to speed, here's my review of Hourglass and here's my review of Timepiece. Okay, now that we're all on the same page, let's wrap up this trilogy!
Infinityglass is told through the eyes of Dune and Hallie. It isn't spoilery to say this, because it's on the book jacket summary and basically right at the beginning of the book -- Hallie is the Infinityglass. What's interesting is how you we come to see how she and her family and friends weave into the lives of the characters we know from the first two books. Infinityglass takes place in New Orleans, and it was neat to experience the city through Hallie, who has lived there all her life, and through Dune, who has just moved.
Honestly, though, Timepiece is still my favorite book in the trilogy. This story just seemed like a love story between Hallie and Dune. That's all good and fine, and I did enjoy seeing the relationship progress, but because of that the first half of the book felt detached from basically the rest of the trilogy. Dune was not a major character in the first two (though he was there) and Hallie wasn't there. The two of them talk a little bit about the Infinityglass in the first part of this book-- but only a little. Mostly we just see them work through their sexual tension and then finally admit that they like each other.
The second half was interesting, because as I said earlier, it was neat to see all the connections come together. And the end was satisfying enough. I'm glad everyone at the Hourglass will have their happily ever after.