Given Hollywood’s top operating principle, that only family movies make the big bucks, there are surprisingly few films in theaters right now suitable to entertain whole families. The Golden Compass and Enchanted are already old news, National Treasure isn’t interesting for young kids, and just because your spawn want to see Alien Vs. Predator or Sweeney Todd by no means makes them suitable. So by default, The Water Horse ought to be a big hit, if audiences manage to find their way to it despite a lukewarm publicity campaign and obscure title. Loathe as I normally am to spoil any of a movie’s surprises, I don’t think I’m doing either audiences or the film a disservice by saying that it’s the story of a Scottish boy who finds and raises a baby Loch Ness monster. Alex Etel, last seen as one of the two kids trying to spend a bag of about-to-expire pound notes in Danny Boyle’s Millions, stars as Angus, who lives on the rural estate where his mother (Emily Watson) is the housekeeper. The film takes place during the darker days of World War II, and Angus is both perturbed by his father’s long absence and the arrival of a platoon of soldiers to turn the estate into an outpost to monitor German submarines. (It’s equally possible that this unlikelihood may represent poor scripting in padding out a thin children’s book or a dig at the cowardice of the platoon’s blue-blooded commander—the movie has a notably unheroic view of the military.) The broad outline of the plot isn’t terribly surprising (E.T. and Free Willy), but the critter itself is adorable in its various sizes, the scenery (as much New Zealand as Scotland) is gorgeous, and there are enough intriguing grace notes (like the ruins at the bottom of the lake) to pique adult interest when the plot goes on autopilot.