The best single word to describe Collier's stories, written between the 1930s and 1950s, is, I think, 'fantastic'. Collier's stock in trade is the unfamiliar and the bizarre - recurring figures and themes include devils and angels, the Devil himself (usually in his guise as arch-tempter), journeys to hell, unhappy marriages, partner-swapping (intentional and otherwise), murders of all kinds, super-natural (and often malevolent) animals, and unconventional, obsessive loves - and his work is suffused by a sense of the surreal.
Some of the stories start with a portrait of normality before an element of the absurd or the unfamiliar violently intrudes, while others commence from an obviously fantastic premise and then unwind further and further from that starting point, but both 'species' have real narrative momentum, giving them a sort of 'if-I-first-suspend-my-disbelief' plausibility and, incidentally, making them very easy to read. The pleasure to be derived from Collier's stories is also enhanced by the cool (in the sense of 'detached and critical'), sardonic, satirical narrative voice in which they're related, and the sly - and sometimes laugh-out-loud - humour which often makes itself apparent along the way.
The stories are quite short - they average about eight or nine pages in length, and this edition of Fancies and Goodnights contains fifty-odd - yet never seem to stint on context or detail, and usually turn on an unexpected (yet almost always, in retrospect, entirely appropriate) twist. In Collier's world, unpleasant and morally corrupt characters often (but don't always) get their just deserts; on the other hand, sometimes perfectly unobjectionable people come to horrible ends. In some stories, love triumphs; in others, it is (quite literally) trampled upon and beaten to death. Sometimes the Devil can be cheated; in other instances, the final scene sees the central character going straight to Hell. And the cumulative effect of these fractured reflections of the everyday is mildly unsettling, and dislocatory, to say the least.
Some favourites: "Gavin O'Leary", which follows an ambitious flea who pursues a screen idol to Hollywood, suffers many tribulations, and finally finds true, mutually parasitic love; "Fallen Star", in which the designs of an "elderly, fat and most unprepossessing" devil on a young she-angel are foiled when the devil permits himself to be psychoanalysed by the she-angel's human lover; "Season of Mists", wherein a strangely insubstantial cad finds that his deceitful double life has unexpected repercussions in terms of Other-ness; "Evening Primrose", depicting a clandestine, intensely class-conscious society which exists in the shadows of department stores and enforces its social rules with terrifying harshness; and "Great Possibilities", a wry, uncharacteristically gentle meditation on compulsion (in the form of pyromania), memory and renewal. Really, though, there are so many others which are just as good, and in which the sting is just as sharp. In a foreword, Ray Bradbury professes surprise that Collier's name is not better known, and, having had this first taste of his abilities, I can only agree.