Philip Warwick is an ordinary looking man with an ordinary life but he brings to Ashton-Kirk a mystery that will put that investigator a most challenging case. Warwick talks about a friend of his, young Stella Corbin, who is the niece of a well-known and very outspoken inventor and 'scientific anarchist' who she fears is about to be murdered. Add in the strange happenings Warwick mentions taking place round the threatened man's house and Ashton-Kirk is certain foreign agents are at work.