Is calling a film’s narrative structure “airtight” a compliment or a pejorative? Clockwork storytelling can entertain, yet such mechanisms can also seem overly constructed, like one of those essays that gets high scores from the SAT folks. If one of those essays became an animated movie it might be Epic. This rather average-scaled adventure concerns a young woman, MK (voiced by Amanda Seyfried), who visits her father, Bomba (Jason Sudeikis), with hopes of talking him out of his reclusive lifestyle. Bomba’s life’s work is attempting to prove that a fantastical society of miniature people lives in the nearby woods. MK’s cynicism turns to belief when she is shrunken down to thimble-size and winds up a player in the battle between the forces of good and evil in the forest world. Christoph Waltz has tons of fun in his role as the chief baddie, surely the best-cast voice here. Epic, presented in 3D, is noteworthy for its depictions of characters flying (birds are the energy-efficient vehicles of this green society) and swinging through the woods, with image depth that practically hypnotizes. With its array of goofy sidekicks (Aziz Ansari as a slug almost runs away with the whole picture) and carefully crafted relationships, Epic certainly manages to tell a compelling tale. Yet in a post-Up era where animated films can pulse with profound truths, the question remains: Is mere entertainment enough?