No-one is more surprised than time-travelling detective Ali Dawson when Charles Dickens suddenly turns up on her doorstep a few days before Christmas. The Great Writer is as baffled as she is as to how he got there. Ali takes him in, despite being preoccupied with a new cold case around the murdered artist Sylvester Strong. Dickens is a rather demanding house guest. However, as a detective, he shows distinct promise and together they embark on finding the truth behind the appearance of new paintings by the deceased artist. On top of that Nell, the daughter of Ali's best friend Meg, has vanished without a trace. As the whole of London is in full festive swing and preparing for the most special day of the year, Ali and Dickens are exploring the town, desperate to solve not just one but two crime cases. Will they succeed before Christmas Day arrives and more importantly, will Charles find a way back home?