In it, an Astronomer spots a star that disappears. This star is 1,500 light years away. He travels to another star system (Humanity is a multi-system species) and observes the star again, at just the right moment to see the light from its disappearance. It disappears within a couple of seconds, as does a nearby star. But its infrared output is undimmed.
This kicks off an epic, and I really do mean epic, space opera. Peter F Hamilton is really great at such stories, and I love this pair of books so much that I've read them about a dozen times each.
Highly recommended!