Published in 1953, Arthur C. Clarke’s “Childhood’s End” has flummoxed attempts to put the story on screen, doubtless heightening anticipation for this six-hour adaptation that Syfy will air over three successive nights. Yet given the bleakness and cerebral nature of Clarke’s book about visiting aliens, human evolution and the price of utopia, the filmmakers have not surprisingly rounded several edges and sought to bring more emotion to the characters. However purists receive that, the result is a provocative but not fully satisfying science-fiction vision, complicated in part by all the movies the novel influenced that were produced in between.

Stanley Kubrick, notably, was among those who considered taking a whack at Clarke’s book, before turning his attention to what became “2001: A Space Odyssey.” The themes in both certainly overlap, with alien visitors, known as the Overlords, coming to an Earth riven by war, general unrest and climate change (the story has been brought into contemporary times), offering to spare mankind from those ills.

That news is delivered to understandably skeptical humans by Karellen (Charles Dance, fresh off “Game of Thrones,” and a splendid casting choice). Identified as the supervisor for Earth, he explains his mission as follows: “We’re not conquerors. We’re enablers. We’re going to help you change.” With apologies to “The Twilight Zone,” at least he didn’t say, “To serve man.”

In one early departure from the book, instead of choosing the Secretary General of the United Nations as his conduit, Karellen picks a Missouri farmer (Mike Vogel), presented as a kind of Everyman to help the Overlords – who at first opt to remain unseen – demonstrate their benign intentions. While Clarke abandoned characters as the story spanned decades, this TV version tries to remain more cohesive, in part by truncating the timeline, which creates some awkwardness in stringing together those slightly disjointed plots.

Those include, but aren’t limited to, a skeptical scientist (Osy Ikhile) eager to study what the Overlords really have in store, even as human curiosity and inquiry begins to fade; and a family whose children begin behaving strangely, drawing inordinate attention from a famous scientist (Julian McMahon) who aims to do Karellen’s bidding.

Writer Matthew Graham (the U.K.’s “Life on Mars”) and director Nick Hurran (“Sherlock”), both veterans of “Doctor Who,” endeavor to bring tension to what’s happening at every turn, which, given the source material, is clearly a challenge. In the process, they have inevitably sacrificed some detail and nuance, creating what, even at roughly four hours sans commercials, feels a bit like the CliffsNotes version of “Childhood’s End.”

Nor does it help that there are so many echoes of more broadly pitched movies, especially in the opening chapter. Perhaps that’s why the handsome production is, visually speaking, a mishmash of “Close Encounters of the Third Kind” and “Independence Day,” with nods to narrower fare like “Children of the Damned” (and one overt reference to the movie “Signs”).

If nothing else, Syfy deserves plaudits for tackling a project with such sweeping ambition, especially when few of its recent offerings, including several shows seemingly ordered primarily due to their Canadian financing, have done much justice to even the bastardized version of its name. Dance, moreover, brings immense gravitas to Karellen, and the first-night reveal – especially to those unfamiliar with the source – should deliver a pretty formidable wallop.

Still, not every book is particularly well suited to cinematic adaptation, and just as “2001’s” more surreal aspects have provoked plenty of debate, Clarke’s story defies conventional expectations. The miniseries is certainly watchable, and the experiment represents a valiant effort. But in TV terms, “Childhood’s End” ultimately feels trapped between worlds – a program that’s alternately oversimplified and perhaps a bit too evolved for its own good.