Listening to this book on any other day except the weekend might not be a problem at all because it is not a very long book and it will have no impact on your work the next days. There are assassins who are not killing the innocent rather they are after the aliens or invaders who are trying to take over the planet.
The enemy has won apparently and the humans are fighting a lost battle according to many people but still, the assassins see hope in everything and they think that they can outclass anyone if they get the chance. This short little story will not allow you any kind of break at any place and the audience will love the flow of the story by all means.