A General is the latest officer to die by deliberately putting himself at risk so the Avengers investigate. Groves was well-regarded by his troops but his Major is cagey, so Steed tells Emma to show him her bumps - the Major is interested in phrenology. They discover Major Robertson is a member of a secret society which allows Army men to experience the adrenalin rush of being in battle again, by performing crimes and taking risks.
The idea of a society of danger seekers is really interesting, especially when it's centred around the military. Adrenalin isn't a subject used in 1960's TV series. The Avenger has fantastic concepts- Nigel Davenport's character feels that there isn't enough wars for one to get danger - it's an ok episode, though a little uneven as the first half isn't very sharp or as engaging as the latter. Loved the danger apparatus Emma is forced to go on as an initiation into the society. There's a lively fencing sequence and loved how the villain was see-sawed into the electric portion of the apparatus- the saying "hoisted by one's own petard" comes to mind.