"The Lambda Factor" is the nineteenth episode of the second series of Space: 1999 (and the forty-third episode overall of the programme). The screenplay was written by Terrance Dicks; the director was Charles Crichton. The final shooting script is dated 6 August 1976, with amendments dated 2 September, 15 September, 27 September, 28 September, 29 September and 5 October 1976. Live action filming took place Wednesday 29 September 1976 through Friday 15 October 1976. Story It is 2308 days after leaving Earth orbit, and the Moon is drifting through an empty region of space the Alphans have dubbed the 'Peace Zone'. Contrary to expectations, the past several days have not been uneventful; the community is plagued by sporadic disturbances and petty irritations. Doctor Helena Russell is currently dealing with a matter of discipline. Medical technician Sally Martin has repeatedly failed to complete an inventory of the medical stores; as a result, she has been ordered to finish it during her off-duty time. Devastated after a broken engagement, the girl sulkily carries out the assignment. Alone in the storeroom, Sally is the focus of a series of disturbing events. A heavy jar slides off a high shelf, narrowly missing her. A cabinet door spontaneously slides shut, almost catching her fingers. Finally, the lights die and a sourceless wind invades the room, sending loose objects flying at her from the shelves. After the exit hatch closes and locks on its own, a panicked Sally takes refuge in an adjoining compartment. While she cowers in a corner, the hatch is torn in two by an unseen force. As the wind surges in, a tremendous pressure crushes the life out of her. During this tragedy, John Koenig is sleeping fitfully. In his dreams, he is tormented by the ghostly image of a woman—who accuses him of having killed her. An urgent call from Helena awakens the Commander. Arriving as the stretcher team collects Sally's body, Koenig joins the doctor and Tony Verdeschi in Medical Stores to survey the chaotic scene. Haggard and ill-tempered, he snaps at Helena to conduct an immediate autopsy. In the event something hostile has broken in, Koenig orders the whole of Moonbase Alpha searched. Not dismissing the possibility of foul play, he also asks for a dossier on the dead girl. As the Moon approaches a gaseous formation filled with electrically-charged particles, the Command Centre staff frets over a number