Sister Boniface is called by DI Gillespie to the home of minister of defence Charles Streatham, where guest Mary Sparkes has been found dead at the bottom of a staircase. Quickly assessing Sparkes has been murdered by poisoning rather than by a fall, Gillespie and DS Livingstone have to identify the murderer among the persons in the house - one is reporter Ruth Penny, disguised as a maid and looking for a scoop