Critically speaking, I don't suppose this novel will recover from the kicking M John Harrison recently gave it in the Groaniad. Nor should it. It is a rubbish confection about Nazi clones and manmade flying saucers in the jungle, written by Wyndham at the same time as he was working on the superb Day of the Triffids. That he found he couldn't sell it, even with Fred Pohl working as his US agent, doesn't surprise me in the least (it languished, unpublished, at Liverpool University Library until a university press edition last year; now Penguin have given it a mass-market paperback roll-out). Harrison thinks the problem is its pulp-cliché flatness and style, and he's not wrong; likewise Christopher Priest, who, by the way, makes an admirable job of putting together an introduction that isn't just the phrase 'awful book, awful book' over and over, identifies the main problem as tonal. Wyndham tries to reproduce a snappy hard-boiled idiom from US gumshoe crime pulps. He fails, and instead we have half-arsed non-noirisms of the 'you can go jump in the glue pot for all I care' sort, and lots of stuff like this:
Seeing as there is more empiric bunk talked about sex than pretty near anything else, you might think I'd not fall for my cousin Freda. On the moronic theory of opposites invariably attracting, I ought to have been panting after some cute, doll-sized brunette -- like all Patagonians ought to be crazy over Pygmies, or all Texans over Japanese girls. Priest is right that this ill-advised tone dissipates somewhat in the second half of the book, but it hangs around long enough to ruin the whole. Sentences such as 'it made my heart kind of flop when I spotted her'  have the disingenuous feel of a profoundly artful writer essaying artlessness; a sort of ghastly literary coquetry, like an attractive forty-year-old woman acting like a fourteen-year-old.
Still, I'm not sorry I read Plan for Chaos. I'm presently writing introductions for Folio editions of three Wyndham novels (Triffids, Chrysalids, Midwich) and it was, if nothing else, interesting to see recurrent Wyndham themes in nascent form. For instance there's the horror the narrator-protagonist Johnny Farthing, feels at the prospect of clones replacing natural births ('visions of a regimented world, of corps fitted, as among ants, to work, or guard, and with no other interest or purpose in life', 155); or to be precise, the way this possible fate is discussed in explicitly racial terms. Farthing, in conversation with a government official, earnestly urges a kind of ethnic cleansing of all the clones:
'Once that [cloning] HQ is found, it should be utterly destroyed, at once, and all knowledge of the Eidermann process with it. I can't help it if that would entail the deaths of hundreds of my cousins -- the thing's too dangerous for that to count ...'Love-interest and fellow clonee (is that a word?) Freda takes a different perspective: the clones should be encouraged, as a potential 'race of supermen.' When Farthing objects that there are too many people in the world already, she retorts, 'yes, but only racially fourth- or fifth-rate people.' And discussing this pleasant debating point amongst themselves, the two of them go off to have kids together, and the novel ends.
'Mr Farthing, don't you think you're slightly --?'
'No, I'm not. The thing is in the first stage of a potential destruction of the species. It is our duty to scotch it completely.' 
What interests me about this is the way it looks forward to similar moments in later novels (the speech of the Sealand woman at the end of Chrysalids, the destruction of the children in Midwich) in which the (I'm happy to believe) thoroughly decent and humane Wyndham dramatises the mindset precisely of a Nazi, anxious at the threat to 'our race' posed by certain populations of otherwise normal looking adults and children.