The book is a graphic novel about mathematicians.
Specifically, the book is about Bertrand Russell, about the writing of Principia Mathematica, about Ludwig Wittgenstein, and about Kurt Godel and the Incompleteness Theorem.
As it turned out, I mostly knew the history-of-philosophy and history-of-mathematics story lines of the book, as I happened to have taken undergraduate classes in this area in college in the 80's. And I was particularly fond of the Incompleteness Theorem so I actually paid attention in that class!
I knew rather less about the social history of Russell's life, about his personal misfortunes, and about his biography. Unfortunately, these are areas in which the book exercises a certain amount of literary privilege; as they note in their afterword:
Also, though our major characters are based as closely as possible on their real-life counterparts, we have on more than one occasion departed from factual detail, in order to give our narrative greater coherence and depth.
It's a tricky business, making history entertaining. The book is pleasantly illustrated, and easy to read; it flows along and I finished it in a few days. But for a book about characters who cared so very, very deeply about truth and accuracy, departing from the facts is a treacherous technique.
If you know little about mathematical logic and the underpinnings of theoretical computer science, you will probably find this an interesting book. But you won't learn much actual mathematics; you'll mostly learn about the history of some fairly interesting and noteworthy individuals of 100 years ago.