A colony of rats constitute the characters in this tale, which reminded me a little bit of Watership Down. Twisted Foot is the leader of the Watchers; he's one of the few who has ever seen the outside world. The colony is stratified into slaves/Scavengers, Watchers, Protectors, and Rulers ... and none dare step outside their role.
Until the Two-footers (humans) show up and start building a contraption up above ... and Twisted Foot decides it might be time to actually try to leave the island by swimming to the mainland.
This was not an easy book. There are incredibly violent scenes that show how difficult life is for the rat colony; they are not gratuitous, but they are unpleasant. I became rather attached to some of the characters, which sometimes made it challenging to read about the hardships they faced.
The plot and characters were well-developed, and give a backstory to a real place that I might not have considered. Well done.