I genuinely have no idea how to describe this book (the blurb above warns that it "defies description", so why I'm even bothering I'm not sure.)
For those who don't know, in reality Sacco & Vanzetti were Italian immigrants to America in the 1920s. They were convicted of murder, and during their trial it transpired that they were anarchists. They were sentenced to death and executed, to outcry around the world that stemmed largely from the (probably accurate) belief that their execution was due to their political views rather than their actual guilt.
In the alternative reality of the novel, Sacco & Vanzetti are not anarchist activists but silent film stars, in the line of Buster Keaton, Harold Lloyd, Laurel & Hardy and so on. The novel charts their lives (in a non-chronological order) and "relives" some of the situations that they find themselves in. Obviously all these situations are fictional but they are woven very, very cleverly into genuine scenarios and often have cameos from real individuals (Bob Hope being the one that most people would have heard of.) The chapter that deals with their later years is written so well as to be genuinely touching; it would be interesting to change the names and offer it to someone as an account of the last days of Laurel & Hardy, and see if they twig it's untrue - I think that they might not.
Having said that, the novel's structure is confusing (possibly a nod to the anarchist side of things?), bumbling from incident to incident and being distinctly different from, well, everything. It's hard to say if this is a plus or a minus. Given I'd read this book again, I'll count it as a plus. Any reader, however, is unlikely to emerge from it with any sense of...anything. It's really, really, really odd. But it's well written.