Miracle on Regent Street by Ali Harris

the long version

For the past two years, Evie Taylor has lived an invisible existence in London, a city she hoped would bring sparkle to her life. But all that is about to change. For winter has brought a flurry of snow and unexpected possibilities. Hidden away in the basement of Hardy's - once London's most elegant department store - Evie manages the stockroom of a shop whose glory days have long since passed. When Evie overhears that Hardy's is at risk of being sold, she secretly hatches a plan. If she can reverse the store's fortunes by December 26th - three weeks away - and transform it into a magical destination once again, she might just be able to save it. But she's going to need every ounce of talent and determination she has. In fact, she's going to need a miracle.