During a Christmas party, Euphemia Martins - together with Bertram Stapleford and manservant Rory McLeod - is tasked by the slippery government agent Fitzroy with doing a little snooping at the Staplefords' Highland Lodge. When Euphemia discovers the purposes of the charade for which she has been demoted back to a maid, she is furious. There are plans afoot - plans which involve signing the Official Secrets Act... Meanwhile, Rory still isn't speaking to her and Bertram is more interested in growing his awful new beard. When the inevitable dead body turns up, they must all work together or find themselves jailed for murder.