Alex's second attempt to break out of Furnace Penitentiary failed. This time, his punishment will be much worse than before. Because in the hidden, bloodstained laboratories beneath the prison, he will be made into a monster. As the warden pumps something evil into his veins--a sinisterly dark nectar--Alex becomes what he most fears . . . a superhuman minion of Furnace. How can he escape when the darkness is inside him? How can he lead the way to freedom if he is lost to himself?

Forever altered by his experience in Furnace Penetentiary, Alex has done the impossible and escaped. But the battle for freedom is only just beginning. Charged with his superhuman abilities, Alex must uncover the last of Furnace's secrets--the truth about the man who built the prison, the man known as Alfred Furnace. And to do that he must stop running and finally confront his greatest fears.

Alex Sawyer has escaped his underground nightmare to discover the whole world has become a prison, and Alfred Furnace is its master. Monsters rule the streets, leaving nothing but murder in their wake. Those who do not die become slaves to Furnace's reign of cruelty. Alex is a monster too. He is the only one who can stop Furnace but in doing so he could destroy everything. Is he the executed or the executioner? Who will die? All Alex knows is that one way or another, it all ends now.
Execution is an Escape from Furnace book from Alexander Gordon Smith.