This was the first of Mark Watson's books that I have read, and I was very glad I did.
First of all, if you have managed to avoid hearing much about the story so far, keep it that way and let the story unfold as it was intended. I will try to keep my review spoiler free, although this is no mean feat with a book like this!
The 'Knot', in the title of this book refers both to "tying the knot" (the main character is a wedding photographer), and also to the kind of knot one gets in the pit of their stomach. Dominic has had a knot in his stomach since an early age, and the novel follows him throughout his life, rarely explicitly confronting his 'knot', but showing how much it affects the way he lives his life.
The nature of Dominic's secret is something that is one of society's biggest taboos, but Watson's writing is completely unsensational, avoids loaded language and does not judge the characters, and I found myself sympathising with and pitying a character who in many other authors' hands would be completely unrelatable.
The book is at times - as you would expect from someone as witty as Watson - very funny, but at other points, it is completely heartbreaking. It is a fascinating and involving story and I would recommend it to anyone able to approach a very human story with an open and empathetic mind.