Business executives are being murdered at a rather alarming rate, so Steed and Mrs Peel are called in to investigate. They discover that the perpetrators are a group of women who are chafing under the bonds of a patriarchal system that keeps them subservient. These women have been trained first to create filing and accounting systems so baroque that only they understand them, and then to murder their bosses and take over the businesses themselves, since at that point the women are the only ones competent to do so.
The ringleader of the group of women turns out to be not another woman disaffected by patriarchy, but rather a man named Henry. Henry is a ventriloquist, and he gives orders to the women by means of a ventriloquist’s doll. The doll is dressed and speaks as a female, and is named Henrietta, after Henry’s late wife. Although the women see the doll when they have their meetings, they do not realize that Henry is the one supplying her voice: they think there is another woman somewhere that they have not yet seen who is speaking through the doll, and who is the actual leader of their group.