In The Invoice, Karlsson illustrates how much more we would value moments of enjoyment if each and every one of those moments came at a price. Our protagonist exemplifies exactly how to live a fulfilling life with minimal effort, but there's a catch: for him, it has cost. As he fights to have the bill for his life reduced, he reflects on the greatest and worst moments of his life. He comes to realize that although he has suffered (as we all have), his suffering has been mostly beneficial. But how will he pay for it?