'Mrs MacBain, thank god it's you.' Without another word, he grabbed her arm and pulled her into the room, locking the door behind them. Mrs MacBain turned around, clearly offended at being manhandled, but then gasped, 'Is that blood?'

Loch Down Abbey is full of guests for a Highland Ball. Including several uninvited members of the Inverkillen clan, the Abbey's former residents. Housekeeper Mrs MacBain thinks her biggest challenge will be finding suitable rooms for everyone and keeping the peace at cocktail hour.

Until the morning after the ball, when one of the guests is discovered inside the Abbey's library - as dead as a doornail.

Who would have had motive to want them dead? And how did they manage to commit their crime and escape while keeping the door locked from the inside?

With an Abbey full of suspects and secrets, it is down to Mrs MacBain to catch the killer before they strike again...