"An Accidental Man" is the first book I've read by Iris Murdoch, and it exceeded my expectations enormously. The plot by itself was structured well, but I think the most impressive aspect of this novel was the character development. In less than four hundred pages, Murdoch involves a wide "menagerie" of characters, and each character's personality is so well evoked that by the ending the audience knows each one intimately enough to judge each one and form their own conclusions. The coherent way Murdoch stacked the novel together also benefits the process.
The story involves quite a few strands, the main ones being Ludwig and Gracie's, Matthew and Mavis', and Austin and Dorina's. Although Austin is cited as being the "Accidental Man" in the blurb, I think that each man stated at the beginning of this paragraph could be considered equally "accidental". All of these men and their women have serious issues, and often end up in even graver situations by pure chance, mostly as a result of eluding themselves "accidentally" to the point of no return. I say "mostly" because it's a lot more complex than that.
To summarise it succinctly, without giving too much away: the story's events are expressed through an interesting mixture of third person narration, personal letters, and the excessively gallant, hearsay-concentrated dialogue spoken at social occasions ("they're rich now but, I think, still are socialists"). Murdoch makes up for the not too exciting plotline by making a very thorough humanistic analysis of characters stuck in deep problems, and convincingly writes how they solve their issues. In the end, no one looks outstandingly innocent or passive, since they are all human characters trying to solve their problems, as a rule trying to cause more pain to an outsider than to oneself.