Freudians should be cheered to learn that ol' Sigmund prospers at the multiplex, at least in child-friendly cinema. The Spiderwick Chronicles, an extravagantly oedipal fantasy flick based on the popular children's novels, comes stuffed with dads ripe for slaying, a freshly single mom (Mary-Louise Parker), and one majorly split personality in the form of her twin sons. There's a carelessly tacked-on big sister — a waste of the promising young actress Sarah Bolger — but it's the boys, an angry rebel and a bookish nerd, both played with laid-back intelligence by Freddie Highmore, who drive the rather thin story.
Jared and Simon Grace are steamed over their family's abrupt move — minus an absent father — from New York City to an old, ramshackle rural New England house, which once belonged to mother Helen's great-uncle Arthur Spiderwick (David Strathairn). A naturalist who vanished without a trace years ago, Uncle Spiderwick left behind a young daughter — but it would ruin everything if I told you who plays her. That lost little girl eventually becomes one of many truth-tellers designed to set the boys free.
Their world upside down, the boys have only their fears for company, and you'd have to be pretty unschooled in fairy-tale protocol to be shocked when a wee gnarled creature named Thimbletack, voiced by Martin Short, pops out. This temperamental house goblin squeakily warns that reading the dusty field guide they've found in the attic may open up worlds the boys don't want to explore. Like all bibles and self-help manuals, the guide, written by great-great-uncle Arthur before he disappeared, offers a forked road map to good or evil — or both — depending on who gets his hands on it.
There also is a shape-shifting demon to be slain (Mr. Id himself, Nick Nolte in stringy white hair), a monster who, Freudians may note with delight, morphs into the boys' absent father — and, when that doesn't frighten them off, a phallic serpent. Much of the movie sustains the delicate balance between scary fantasy and human story. But CGI is a seductive mistress, and toward the end, Spiderwick bogs down in a crescendo of effects and action before fizzling tearfully to black.