Only the most extraordinary circumstances can reunite the Birch family for the holidays…

It's Christmas, and for the first time in years the entire Birch family will be under one roof. Even Emma and Andrew's elder daughter—who is usually off saving the world—will be joining them at Weyfield Hall. But Olivia, a doctor, is only coming home because she has to. She's just returned from treating an epidemic abroad and has been told she must stay in quarantine for a week…and so too should her family.

For the next seven days, the Birches are locked down, cut off from the rest of humanity, and forced into each other's orbits. Younger, unabashedly frivolous daughter Phoebe is fixated on her upcoming wedding, while Olivia deals with the culture shock of first-world problems.

As Andrew sequesters himself in his study writing scathing restaurant reviews and remembering his glory days as a war correspondent, Emma hides a secret that will turn the whole family upside down.

In close proximity, not much can stay hidden for long, and as revelations and long-held tensions come to light, nothing is more shocking than the unexpected guest who's about to arrive…