He calls himself the Big Friendly Giant, and he is the only soul populating the rocky seaside Giant Country who doesn't live the life of a voracious cannibal. His only companions are the children he occasionally snatches from London. Alas, with the rest of his kind preferring the taste of humans, they don't always make it. Based on Roald Dahl's 1982 children's novel, "The BFG" is a forlorn family film about a friendship that can only last in an unconventional manner. As directed by Steven Spielberg (2011's "War Horse") and written by the late Melissa Mathison (1982's "E.T. the Extra-Terrestrial"), the picture is a quaint and talky two-hander for the majority of its running time, but not without tinges of that old Amblin magic. Said whimsy, however, is often overshadowed by a melancholia its makers aren't fully prepared to acknowledge or deal with head-on.

There is no period more mysterious than the 3 a.m. witching hour, a quiet time which 10-year-old insomniac Sophie (Ruby Barnhill) embraces as her very own. On one particular early morning, the unexpected occurs: from her orphanage's bedroom window, she spots a giant (Mark Rylance) prowling the city streets. When BFG catches Sophie spying on him, he scoops her up and spirits her to his cavernous home in the faraway Giant Country. At first frightened of her abductor, the young girl eventually realizes how gentle-hearted he is, an outsider who yearns for acceptance and love. Determined to put a stop to the other bullying, child-nibbling giants, Sophie forms a plan so wild it just might work. Success will come with a price, though: BFG will have to find the courage to reveal himself to the outside world.

"The BFG" is episodic and loosely plotted, relying upon the relationship between the plucky Sophie and a gargantuan older man she names BFG to carry the film through its meandering narrative. There are weaknesses to the script—the film features no scenes of the crummy life Sophie claims she has at the orphanage to bring perspective to what she stands to gain from being anywhere else but there; the key appearances of the Queen of England (Penelope Wilton) and aide Mary (Rebecca Hall) are undernourished, not properly setting up Sophie's crucial bond to them—but Steven Spielberg's dreamy vision is certainly winning. Any movie that can prominently incorporate a fizzy green beverage called frobscottle and the over-the-top flatulence (called "whizzpoppers") it causes without coming off as juvenile or scatological must be doing something tonally right.

Newcomer Ruby Barnhill is a sweetheart as the clever, thoughtful Sophie. She and a CG-animated Mark Rylance (collaborating again with Spielberg following his Oscar-winning work in 2015's "Bridge of Spies") are the heart of the project, and it's a good thing since every other actor on hand is virtual window dressing. Barnhill has a natural-born talent where every moment on screen is an honest one. In a performance-capture turn that brings his movements, facial features and emotions to unmistakable life, Rylance blesses uneducated aspiring writer BFG with an endearing innocence. Both are likable and sweet, playing believably off one another even when the visual effects threaten to trump them. The technical wizardry which brings BFG and the other oafish giants to life as they intermingle with smaller, human-sized performers isn't always seamless—it is pretty clear they are, in fact, computer-augmented creations—but their expressiveness is every bit as real as their live-action counterparts. In small roles, Penelope Wilton (2005's "Match Point") displays a mischievous comic verve as the Queen, while Rebecca Hall (2015's "The Gift") is wildly underutilized as Queen's aide Mary.

In today's kinetic, fast-paced world of family entertainment, younger audiences may have disparate reactions to "The BFG." Some will be taken by the film's protagonists and the sheer control and wonder director Steven Spielberg cooks up, while others will lose patience with its slow pacing and slack story. There is a warm, bittersweet quality in the picture's bones, and also a welcome darkness that may frighten more impressionable viewers. A safe cinematic scare here and there never hurt anyone. Unfortunately, if Spielberg has gotten Sophie and BFG just right for this adaptation, he and writer Mathison do not seem to be willing to confront the sad insinuations of a finale that, without giving too much away, hopelessly isolates BFG even more than he was at picture's start. As a fairy tale involving an unlikely cross-species friendship, "The BFG" is far from the instant classic "E.T. the Extra-Terrestrial" is. The film has its pleasures all the same, and a wide-eyed earnestness.