Crash III by Michael Robertson

After witnessing his father's murder and his home burned to the ground, Michael is left wandering the violent streets of London alone.

Having been captured and managing to escape the clutches of the most heinous of men, he's terrified of recapture.

All Michael wants to do is find somewhere safe. Somewhere he can call home.

To do that he must survive in a city where he’s the weak and the hunted---with no family or friends to help him.

When he meets someone who offers him hope, someone who's different from all of the other people in this broken and violent world, he realizes he needs to trust someone... 

But if he lowers his guard to accept that help, he could end up at the warehouse again. 
He’d rather die than go back there.

Crash 3: There's No Place Like Home is a dark post-apocalyptic tale.