Jack and the Beanstalk is one of the few English folktales Americans know by heart. A peasant boy sells his abusive guardian's livestock for some beans, the beans get wet, a beanstalk grows, and off he goes to rescue a princess from a bread-crazed giant in the sky. Combining that G-rated Beanstalk yarn with all the decapitations and anus-stabbing of the true Arthurian legend, Jack the Giant Slayer is a grimy retelling of the children's tale…in 3-D.

The film opens in the kingdom of Cloister. The kingdom fought a terrible war with a horde of giants many years ago, so long ago that few believe giants ever existed. All that remains is a children's book written in clerihew verse—well, that and some magic beans.

The titular Jack, played by Nicholas Hoult (About a Boy, Warm Bodies), is an awkward farm boy who has grown up obsessed with this children's tale, as has Princess Isabelle (Eleanor Tomlinson), the rebellious descendant of the king who defeated the giants. Alas, the princess is unhappily betrothed to the ambitious nobleman Roderick (Stanley Tucci, sporting the goatee of evil). Tucci is given the thankless role of a cartoonish bad guy who does evil things to advance the plot.

Said plot plods along, until the beans start sprouting. Given the history of this tale, it's surprising it took until 2013 for a major studio to tackle the rapidly growing beanstalk with CGI. It's a spectacle unto itself as the sinewy tendrils rip through the ground, out of the cabin and into the sky. In an equally impressive CGI feat, a giant picks his nose while wrapping Ewan McGregor in a pancake.

It's up to Jack and several others (including McGregor, having fun as an upbeat captain of the guard) to save the damsel in distress at the top of the beanstalk. But the story isn't particularly important, and the film can't decide whether it wants to be serious or tongue-in-cheek. No, Jack the Giant Slayer is focused on moving from one epic fantasy scene to another, whether it's McGregor shouting "Tally ho!" as he zip-lines across the beanstalk or a two-headed giant (Bill Nighy) bursting through a tiled floor. And to that end, it's a great deal of fun.

Critic's Grade: B

SEE IT: Jack the Giant Slayer is rated PG-13. It opens Friday at Cedar Hills, Eastport, Clackamas, Cornelius, Lloyd Center, Cinema 99, Bridgeport, City Center, Division, Evergreen Parkway, Hilltop, Lloyd Mall, Movies on TV, Pioneer Place, Sherwood, Tigard.