Six people bound together by a traumatic experience decide to round off a year of group therapy in style. They join each other once more, traveling up to the Scottish Lowlands for a reunion weekend in a 1970s holiday let. Soon a number of mysterious and horrifying events start to expose the cracks in their relationships, and one by one they discover that trust runs but skin-deep. A night of closure turns out to be far more final than they could have anticipated.

In 2013, something terrible is awakening in London’s National Gallery; in 1562, a murderous plot is afoot in Elizabethan England; and somewhere in space an ancient battle reaches its devastating conclusion. All of reality is at stake as the Doctor’s own dangerous past comes back to haunt him.