He's got a knife!" yells little Johnny, retreating from his blade-swinging brother Richard. "Of course he's got a knife!" shouts mum Eleanor. "We've all got knives! This is 1183."
And so we launch into Carry On Up The Aquitaine, James Goldman's Broadway take on English history that offers ripe opportunity for sitcom mugging amidst hokum relating to Henry II, his troublesome three sons, who are vying for his crown, and his vexatious viper of a wife Eleanor who he has wisely boarded up for a decade.
And with what brio and relish this romp is delivered. There are innumerable delights watching Robert Lindsay (Henry II) and Joanna Lumley (Eleanor) duel and joust for the contents of each other's hearts and inventories.
"Every family has its ups and downs," sighs Eleanor, formerly Queen of France, who has been released briefly for Christmas at Chinon.
Not like this, your Majesty. West Wing's politics meets East End ensibilities in a tale of festive feuding that brings to mind slap-happy humdingers in the Queen Vic.
Yes, King Den and Queen Angie have a simmering beef that's about to blow up into an ermine mudfight. But beneath it all, wouldn't you know, there's love - a destructive love that ensures they fight each other to a weary standstill.
Lindsay and Lumley, a double act to cherish, fill their roles like velvet boxing gloves, finding a rare chemistry that is part-poison, part-passion.
And if the play fails to flatter when the supporting cast have their moments it is only to the credit of the headliners.
Tom Bateman, James Norton and Joseph Drake as the fickle sons roar their way to infamy while the French contingent of Rory Fleck-Byrne as King Philip and Sonya Cassidy as pawn Princess Alais aspire to the bombast of Henry and the dry plotting of Eleanor, respectively, but necessarily fall short.
Against a backdrop of a stone-grey set, Trevor Nunn has put Blackadder firmly in the court of King Lear veering (often wildly) from high drama to low farce ("that's what tapestries are for," says one son, ripping down the offending adornment to reveal an eavesdropping sibling).
A couple of clunks. The cast phlegm it up to 11 so early in proceedings they've got nowhere to go when the action gets stickier. And this means the second half lingers like an unbroken high note waiting for a warble.
But this is a production packed with purring delights and rich silliness.
Forget the front room, Chinon is the place to spend a family Christmas this year.
– From November 2011
