The fourth novel in the sequence was published seven years later, with a different publisher. In the meantime, she had written her best-known book The Golden Notebook, which changed the perspective on the last two volumes of this series. In the fourth book, it is nearly the end of World War II and Martha remains unhappily married but has an affair with Thomas Stern who is a Polish Jew working as a gardener. The affair is short-lived but Lessing readily accepts firstly that their communication is telepathic and, secondly, that Thomas dies insane but that his madness is not necessarily any worse than sanity. The last novel is the longest of the series and certainly the most complex. Martha is now in London after World War II She is staying with the Coldridge and, through Martha and the Coldridges, we see the changes happening in Britain and the world during the post-war period. And, once again, telepathic communication becomes the key element for Martha as she establishes a close relationship with Lynda Coldridge in this way and, when there is a nuclear holocaust at the end, it is this method of communication that some of the survivors who had foreseen the catastrophe use to carry on.
The entire five book sequence is, of course, far more complex than I have painted it here. First and foremost, it is a Bildungsroman with a clear feminist perspective. Secondly, it becomes a political statement, from the left-wing point of view, on colonialism and war. Finally - and this is something that comes towards the end with Lessing's changing views and her increased interest in Sufism and the work of R D Laing - there is the transcendental view, the idea that what really happens is not what we see but way beyond that. You may agree or disagree with Lessing's perspective but it colours her novel in way that you cannot ignore. Martha's quest for the four-gated city has been circular rather than linear. There is not a direct progression as in other Bildungsromans but, rather, a more circular development, each stage building on the preceding one. This is not an easy book - particularly the last one - but, apart from The Golden Notebook, the most rewarding.