Many lonely children yearn for a pet to call their own. In “The Water Horse: Legend of the Deep,” based on a novel by Dick King-Smith, a boy, Angus (Alex Etel), finds not only that, but a best friend as well, after the mysterious egg he stumbles across hatches a creature unlike any he’s ever seen. Adorable and full of mischief, his new companion, Crusoe, who looks something like a cross between a dinosaur and a snail, immediately adds spice to his drab life.

Set in 1942 in coastal Scotland, the film consistently evokes an authentic sense of time and place and features remarkable computer-generated graphics work from Weta Workshop, the company responsible for the groundbreaking visuals of the “Lord of the Rings” trilogy.

When Crusoe grows into the magnificent Loch Ness Monster and must be released to sea, its survival skills are put to the test, and the aggressive pursuit of the creature by townspeople and visiting soldiers alike stirs up “King Kong”-esque feelings of dread.

Brian Cox appears briefly, serving as the film’s present-day narrator. His character’s identity offers no surprise — nor does much else in the film — but that detracts little from this family-friendly escapist fare that should enthrall, without insult, fantasy-minded viewers of any age.

“The Water Horse: Legend of the Deep” is rated PG (Parental Guidance suggested). It has mild violence.

THE WATER HORSE

Legend of the Deep

Opens nationwide on Tuesday.

Directed by Jay Russell; written by Robert Nelson Jacobs, based on the novel “The Water Horse” by Dick King-Smith; director of photography, Oliver Stapleton; edited by Mark Warner; music by James Newton Howard; production designer, Tony Burrough; special effects by Weta Digital and Weta Workshop; produced by Robert Bernstein, Douglas Rae, Barrie M. Osborne and Charlie Lyons; released by Sony Pictures. Running time: 1 hour 51 minutes.

WITH: Emily Watson (Anne MacMorrow), Alex Etel (Angus MacMorrow), Ben Chaplin (Lewis Mowbray), David Morrissey (Captain Hamilton) and Brian Cox (Narrator).