It's Christmas at the barn, and the doors are thrown wide open to welcome some very special guests who have brought along cherished items in need of a festive fix. 

Hollywood legend Dame Helen Mirren arrives, along with a beloved but badly broken cello. This beautiful instrument was owned by theatre director Martin Landau, who aged just 14 fled Nazi-occupied Europe on the Kindertransport, carrying with him just a few personal possessions and his all-important cello. But the instrument was brutally broken by Nazi guards prior to his boarding the train, and its neck deliberately snapped in two. Despite this blow, Martin guarded the cello carefully for the remainder of his life, eventually gifting it to Denville Hall, a care home for retired members of the entertainment industries, of which both he and Dame Helen are loyal supporters. Sadly, the cello has remained silent for over 80 years, and the residents would dearly love to see it restored so that they can hear it played for the first time. Dame Helen entrusts luthier Becky Houghton with the huge but delicate task of reuniting the snapped neck, fixing the broken bodywork and giving the cello back its voice in time to spread seasonal joy to the care home residents and their families. 

Also stepping into the magical world of the barn at Christmas is legendary children's author Julia Donaldson, accompanied by Rob Brydon, who plays the part of Reginald Rake in this year's seasonal adaptation of her book The Scarecrows' Wedding. Julia tasks furniture restorer Will Kirk and ceramics expert Kirsten Ramsay with the repair of a toy farmhouse that once belonged to her granny. This crumbling structure enraptured Julia and her sister throughout their childhood, firing Julia's imagination and helping inspire some of her best-loved books. Julia's plan is to donate the farmhouse to a local children's hospice, where she has performed many of her stories. And an already challenging task takes on a whole new dimension when Rob has the brainwave of asking the barn's team of experts to create a series of toy characters for the children to enjoy, based on those in Julia's books. The Repair Shop's expert elves are soon hard at work bringing miniature snails, whales, tiddlers, scarecrows and gruffalos to life! 

Also arriving at the barn is a life-sized mechanical Rudolph belonging to the Leicestershire fire service. This extraordinary reindeer has brought decades of festive cheer to generations of families but is currently in a sorry state, with tangled and matted fur, ears that no longer move, eyes that no longer blink, and worst of all, a red nose that no longer lights up! It takes the combined efforts of mechanic magicians Steve and David, bear ladies Julie and Amanda, master saddler Suzie and metalworker Dom to restore Rudolph to his proud best, ready to strut his stuff on the streets of Leicester this Christmas to raise thousands of pounds for local charities. 

In their packed Christmas schedule, Dom and Will also find time to restore a battered and broken sledge that has been at the heart of one family's Christmases for a remarkable eight decades. And bookbinder Chris Shaw breathes new life back into a torn and tattered carol book that has played a central role in a much-celebrated yuletide cultural tradition in Sheffield.