River Song decides to investigate a temporal anomaly after a Luna University expedition makes some odd discoveries in an old Earth house - pages of her own diary with an inscrutable riddle written across them.
However, her investigation goes badly wrong when she is transported back into the past of the house and gets trapped within its grounds.
The house is the home of the Mortimers and with a limited ability to travel back and forth in time across eighty years and multiple generations she finds herself witnessing key moments in their family history.
If she wants to escape, the words in her diary are not the only riddle she has to solve. But not everyone in the house will survive what’s coming. And not everyone is on her side.