Emma Thompson is back with a second encounter between her somewhat scary nanny and another houseful of unruly kids. As with the first film, a secondary plot feels corny and superfluous, but it's still thoroughly entertaining.
During the Blitz in London, posh children Cyril and Celia (Vlahos and Taylor-Ritson) are sent to stay with their aunt, Mrs Green (Gyllenhaal), on her farm. While she awaits news of her soldier husband, she struggles to manage her three rambunctious kids (Butterfield, Woods and Steer), pay her bills, fend off her financially desperate brother-in-law (Ifans) and keep the dotty local shopkeeper (Smith) from doing something dangerous. The person she needs is clearly Nanny McPhee (Thompson), who arrives with several stern-but-magical tricks up her sleeve.
Thompson's script is what makes this far more layered and enjoyable than most children's movies. Sure, there's a little too much magical slapstick, as well as lots of mud, treacle and poo, but the dialog snaps with wit, allowing the strong themes to emerge organically as the story progresses. And when the plot centres on the children, it's hugely good fun to watch. Less successful is Ifans' subplot, which seems to only barely work up steam before fizzling out.
The title's "big bang" is a reference to bombs dropped on England during the war, which provides the film with a surprisingly intense climactic sequence.
And the period is inventively recreated by the award-winning crew both in the chaotic countryside and a hilariously whizzy tour of London on Nanny McPhee's motorbike. All of this gives the film some surprising moments of dark emotion, as this fragile family awaits news about their husband and father (a terrific flashback cameo by Ewan McGregor).
Indeed, when it's not indulging in flying pigs or dodgy animated elephants, this is a vastly superior family film with first-rate acting from an excellent cast. The adults are terrific (there are several particularly strong single-scene roles), while the children create vivid characters who act like real kids. But it's the story that really gets under our skin as it goes along.
Even the sentiment at the end feels earned rather than manipulative.