Anvil of Stars is the sequel to The Forge of God. In Anvil, a group of 80 teenagers have been plucked from the survivors of earth's destruction and tasked with hunting down and eliminating the creators of the robots that destroyed earth. They are guided by robot overlords who train them for the task but otherwise don't interfere. The book starts sort of slowly, with the first third or so being a "Lord of the Flies" like examination of how these kids would self organize and structure their society. The 2nd half of the book is much better IMO, and when they meet up with another sentient alien species also hunting the killers it becomes difficult to stop reading, as evidenced my finishing the book at 2 AM last night. The 2nd half also becomes a bit of a morality play as the kids wrestle with the decision to potentially kill trillions of innocent life forms that are shielding the killers.
You don't have to read Forge first to enjoy this book, but I recommend it. Forge was so great that no sequel would stand up, and that is sort of the case here. Anvil is fine book and if you are a sci-fi fan you'll enjoy it. Just be warned that you may have to force yourself to slug through the first third or so, but the payoff is worth it.