Book: Mark Lawrence's "One Word Kill"

Publishers sometimes give away free e-books.  I have read a few of these books and have found them a bit shallow but good enough - a piece of literary fluff.  My latest read, Mark Lawrence's "One Word Kill" is an example of a free piece of fluff.

The book follows a teenager diagnosed with cancer who encounters a future version of himself.  This meeting appears as if it should be impossible.  The book uses the infinite universes version of quantum theory which makes it impossible to change your own past but, in the book, the characters discover they can change their past while ast the same time realize the impossibility of this fact.

The book was entertaining.  It was also the first book of a series.  I'm curious how the author makes the impossible possible but I'm not sure if I really want to continue this series.

I gave this book four stars out of five on Goodreads because it was entertaining though I wonder if I'm being too generous.