Fairytale beneficence mixed with Dickensian villains, ending with Christmas Carol-type uplift: the National, previously home to His Dark Materials, certainly knows how to spot a festive family hit.

Returning after a sell-out run last year, Helen Edmundson's adaptation of the Whitbread Award-winning children's book by Jamila Gavin is, largely, a Christmas cracker.

There's all sorts going on in Gavin's intelligent slice of mid-18th century life: child trafficking, the slave trade, Thomas Coram's Foundling Hospital and the music of Handel, for starters.

But, as in all the best stories, scratch the surface to reveal a simple, universally resonating theme of families fractured and reunited, and love lost and found.

The concluding scenes, as a child given up for dead is revealed to be alive, reach an affective pitch unmatched on any other stage this December.

Melly Still's production, busy from the start with novel-compressing short, sharp bursts of action on an ever-moving revolve, attains transcendence. The onstage choir thrills us with excerpts from Handel's glorious Messiah.

Still doesn't have everything as beautifully worked as this, however. The first half, which sees the teenage Alexander Ashbrook abandon an oppressive aristocratic family to pursue his musical dreams, struggles to achieve emotional as well as physical momentum.

Katherine Manners - the choristers and Coram boys are all played by girls - fights a losing battle with the high notes in Alexander's singing, and generally wilts in comparison to Anna Madeley's spirited, sweet-voiced take on this role last year. How such a bloodless creature manages to impregnate Justine Mitchell's feisty Melissa is a puzzle.

The stench of blood hangs over Tim McMullan's marvellously sinister Otis Gardiner as he does away with babies bound for the Coram Hospital. Gardiner's hairstyle may be slicker by Act Two, but his heart is blacker than ever.

The adult Alexander, played by Bertie Carvel (and I question the logic of allotting this character two actors, while Mitchell continues straight through) has to muster some gumption to challenge him. Take a thoughtful older child, a fond grandparent and a large hankie.

• In rep until 22 Feb (020 7452 3000).