A technical film (the first part of a series) apparently aimed at the inexperienced anaesthetist. Most of the film looks at the theory of the stages of anaesthesia using Guedel's chart. This is laboriously annotated with animations to illustrate every reflex present in anaesthesia using the inhalation method. There are four stages of anaesthesia; the third stage is when surgery can commence (this is in turn subdivided into planes). The fourth stage is respiratory failure and potentially death. There are surgical examples throughout.