Steelheart, by Brandon Sanderson and published in 2013, is the first book in the Reckoners, a young adult fantasy/science fiction series. The second book, Firefight, was published in January 2015.
The world changed when a burst of energy in the sky known as the Calamity resulted in normal people suddenly gaining super powers. These people came to be known as Epics. In the post-apocalyptic world Sanderson has created, Epics have used their powers to take over the world, causing the collapse of governments and countries and wholesale destruction. The more powerful an Epic is, and the more the Epic uses that power, the more likely it seems to be that he or she is uses that power for selfish purpose. So simply having and using an Epic power can apparently corrupt an individual. It's like the Force with only the dark side.
What also distinguishes the Epics is that they each have a weakness. It might not be obvious and it might be very hard to figure out, but that weakness is the key to being able to defeat the Epic. That's what the group of rebels who call themselves the Reckoners do: study each powerful Epic to determine his or her weakness, then act on that weakness to assassinate the Epic. Because of this, Epics go to great lengths to keep their weaknesses secret.
Steelheart is an Epic with apparently invincible powers; he's invulnerable to physical harm, can fly, hurl blasts of energy, and turn inanimate objects into steel. So he's pretty much Superman, only in a world without kryptonite. David, now a young man, was only a child when Steelheart killed his father. David has made defeating the Epic his life's work, and he has a start -- he has seen Steelheart, the supposedly invulnerable supervillian, bleed.
In the course of plotting his revenge, he runs across a group of rebels fighting the Epics. This group bills itself as the Reckoners. The Reckoners assassinate Epics. Successfully. They are suspicious of David at first, thinking he might be an Epic sent to spy on them. Once they discover he's just a normal human trying to get revenge on one of the most powerful Epics in the world, they're tempted to leave him behind. Fortunately, David's obsession with Steelheart has enabled him to gather valuable information, information that might actually hold the key to defeating Steelheart.
In some ways this is your average young adult book -- unrequited love and gasping looks a the most beautiful girl ever (David's opinion of Meagan) that on the surface might appear rather thin. But there's some meat here, and to make sure you know what to chew on , Sanderson states it right out:
Epics had a distinct, even incredible, lack of morals or conscience. That bothered some people, on a philosophical level. Theorists, scholars. They wondered at the sheer inhumanity many Epics manifested. Did the Epics kill because Calamity chose--for whatever reason--only terrible people to gain powers? Or did they kill because such amazing power twisted a person, made them irresponsible?
Steelheart was a quick and fun read, if slightly corny and tough to swallow at times (but maybe that's my age talking), that had at its heart some interesting thoughts. I can see a younger teen tearing through this with relish.