If you want to take the kids to a cockle-warming tale of humans and computer-generated critters, do yourself a favor: Skip the singing rodents and head for the baby Loch Ness Monster in "The Water Horse: Legend of the Deep." The movie has as many cliches as "Alvin and the Chipmunks," but they're better cliches and the cast acts like they're fresh. Sometimes that's enough.
"Water Horse" is essentially "E.T. the Extraterrestrial" moved underwater and choreographed by the Scottish Tourist Board. Little Angus MacMorrow (Alex Etel, the wide-eyed charmer of 2004's "Millions") lives in a rambling estate near the loch; it's World War II and his father (Craig Hall), the local laird, is off at war. Angus keeps the old man's workshop clean with a fervor several shades too dark, as his mother (Emily Watson) and older sister (Priyanka Xi) look on with worry.
A mysterious stone washed up on shore turns out to be an egg; it hatches and soon Alex is hiding a squawking, wriggling baby Nessie from his family and the local army garrison headed by Captain Hamilton (David Morrissey), a preening toff. This proves difficult when Crusoe, as Alex dubs the wee beastie, outgrows the guest bath and attracts the attention of the cook's bulldog.
Like its computer-generated star, "The Water Horse" starts out cute and becomes increasingly ungainly. By the time Crusoe has grown to the size of a plesiosaur and been relocated to the open water, it's difficult to believe he could be kept a secret from the grown-ups, harder still to buy that Alex could ride him down to the bottom of the loch without freezing to death.
The movie has enough faith in itself, though, to convince the kiddies, if not quite enough inspiration to hold mom and dad's attention. The grown-up actors turn in discreet and professional performances, with Watson striking muted notes of sorrow that occasionally flower into something bigger and messier. (But not too messy; this is Great Britain.) Ben Chaplin smolders nicely as a scarred young handyman who's in on the secret, and there's a funny bit with a pair of villagers cooking up the famous Nessie image known as "the surgeon's photograph."
Director Jay Russell made "My Dog Skip" and the movie version of "Tuck Everlasting"; like them, "The Water Horse" moves along at a dutiful clip, engaging us without transporting us. The digital effects are convincing - maybe too much so for the youngest children, once Crusoe is full size and the army is firing on him in a panic - but the real-life locations are much more awe-inspiring. Ironically, those locations are in New Zealand. If there's anything in that loch, it's a waterlogged hobbit.
The film's most special effect, at least for the grown-ups, is Brian Cox as the story's narrator, spinning this yarn to a pair of credulous American backpackers from his perch in a lochside pub. Your kids will think he's the real deal, but watch Cox's eyes: He's shoveling pure Nessie manure and having the time of his life. If only the movie were as wicked.
Ty Burr can be reached at tburr@globe.com. For more on movies, go to boston.com/ae/ movies/blog.
