U4 is a post-apocalyptic novel taking place in Europe, mostly in France. A virus decimated 90% of the population and the survivors are mostly teenagers. We follow four characters trying to survive in this dangerous world and maybe trying to save the world.

U4 is a series of four books telling the same story from four different POv’s (and by 4 different authors). I found the concept really interesting and read the one about the character Jules a few months ago. I decided to pick up the one about Koridwen next. What is really interesting about this series is that you can read the books in any order you like. I immediately picked up the one about Yannis next, because it was the last one I had on my shelves (still need to buy the one about Stéphane).

Yannis is the weakest character in these four books in my opinion. At least at the beginning of the story. But Yannis' journey is maybe also the most impressive; he grows so much during this book, especially since the events take place during less than two months. I still have to read the one about Stéphane, but I think she is a strong badass (who has a weak spot as well and I can't wait to read about her!)

Yannis is coping with his heritage, we don't precisely where his parents come from but he mentions the fact that his father cannot write French properly and that her mom used to sing to him in Arab. This heritage of him will actually have an impact on how he is seen by the kids from the poor areas in Marseille. These gangs of poor kids will make the rich kids pay for the lifestyle they use to have and Yannis will be saved thanks to that, because they think he is "one of them"… because of what he looks like. I think this part was really interesting.

The writing style of this book was amazing, I really had a lot of fun reading this and I could not put it down.