In the novel Dead Man's Folly, Mrs Connie Masterton is the wife of a Wilfred Masterton, the Member of Parliament whose constituency probably includes Nasse House and the area around it. They are friends of Sir George Stubbs and Amy Folliat and regulars at the house.
Mrs Masterton is very much in the centre of things at Nasse House and in the early part of the novel is busy organising the fete. often drawing on her husband's political agent Captain Jim Warburton for some chore or other. Of great concern to her is disentangling all the disputes relating to the setting up of the fete, such as an argument between some ladies on where to site the tea tent. This does not, however, prevent Mrs Masterton from getting involved in disputes herself, such as with Sally Legge on where to site the fortune telling tent.
After the discovery of the murder of Marlene Tucker and the disappearance of Hattie Stubbs, Mrs Masterton has very set ideas on how the crimes had happened and what the police should do. She believes, for example, that the police should bring in blood hounds to search for Hattie Stubbs. She knows Major Merrall, the chief constable well, and constantly pesters him about her idea. Poirot observed that the best thing to do when talking to Mrs Masterton is simply to agree that she might be right.
Amanda Brewis considers Mrs Masterton to be the power behind the throne and that her husband owes his position entirely to her. She has all the drive, initiative and political acumen. Even Warburton refers to her as his real "boss". If she is not the boss, then "[s]he should be. She’s the one who wears the pants – and don’t I know it."