off the restraints and grabs his nemesis by the throat. As they grapple, the spirit gains the upper hand and sadistically holds Mateo's face in contact with the sizzling energy field. Both collapse to the floor in a sudden explosion of blinding energy. Mateo dies and the spirit vanishes. When turned face-up, the John and Helana are horrified to see the face and body burned in the precise manner as the spirit his death has exorcised. Cast Starring Martin Landau — Commander John Koenig Barbara Bain — Doctor Helena Russell Also Starring Barry Morse — Professor Victor Bergman Guest Artists Giancarlo Prete — Doctor Dan Mateo Hilary Dwyer — Laura Adams Anthony Nicholls — Doctor James Warren Featuring Prentis Hancock — Controller Paul Morrow Clifton Jones — David Kano Zienia Merton — Sandra Benes Anton Phillips — Doctor Bob Mathias Nick Tate — Captain Alan Carter Uncredited Artists Suzanne Roquette — Tanya Jim Sullivan — Alphan Musician Tony Allyn — Security Guard Vernon Morris — Male Botanist Xanthi Gardner — Female Botanist Valentino Musetti — 'Spirit' Mateo Music Supplemented by the regular Barry Gray score (drawn primarily from "Another Time, Another Place"), English musician 'Big Jim' Sullivan would compose an eerie, atmospheric composition for the sitar to serve as the primary music track. Sullivan, a prolific session guitarist of the time, also appeared on camera—dressed in an Alpha uniform, he was the performer seen playing the piece in the story's opening scenes. Production Notes Script editor Johnny Byrne's idea for "The Troubled Spirit" arose from his desire to write a science-fiction ghost story. He was pleased with the symmetry that organically evolved—the spirit coming to avenge a death that had not yet occurred, and the Alphans, in their attempts to counter the dangerous presence in their midst, actually causing the death they are trying to avert. In the early 70s, the idea of human-plant communication was a popular concept, as was the notion that the human brain contained many underutilised areas which contained paranormal super-powers. Both Byrne and production designer Keith Wilson recall that producer Sylvia Anderson was greatly involved in the creative development of this episode. Mrs Anderson's usual concerns were production design and the supervision of the actors; executive producer Gerry Anderson normally oversaw the writing staff. Her interest in Byrne's tale had her running the story meetings for this instalment, rather than her husband. In 1973, when