the floor begins heaving beneath his feet. At the moment of contact, Atheria vanishes...the Moon ploughing through the space it occupied. Later, Koenig broods as he stares out a window into the empty space. He is joined by Helena, who apologises for her actions. He interrupts, insisting she did nothing wrong. His story was mad. How could anyone possibly know that two planets on a collision course would not collide, but merely touch...? Cast Starring Martin Landau — Commander John Koenig Barbara Bain — Doctor Helena Russell Also Starring Barry Morse — Professor Victor Bergman Special Guest Star Margaret Leighton — Arra 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 Sarah Bullen — Kate Annie Lambert — Main Mission Operative (Julie) Alf Joint — Alphan Man (Balcony Jumping Man) Music In addition to the regular Barry Gray score (drawn primarily from "Breakaway" and "Another Time, Another Place"), music tracks composed by Gray for the previous Anderson productions Captain Scarlet and the Mysterons, Joe 90 and the film Thunderbird 6 were also utilised. Production notes Along with "Black Sun" and "War Games", "Collision Course" is considered to be one of the programme's most successful instalments by actors, crew and fans alike, exemplifying its metaphysical approach to science fiction. Penned by American-born British television writer Anthony Terpiloff, this story would showcase the author's pet theme of the perseverance of faith and trust over logic and reason. This approach would be seen in his subsequent contributions to the series ("Death's Other Dominion" and "Catacombs of the Moon"). The casting of Margaret Leighton as Arra was a coup for the series. The accomplished and prolific British actress had appeared in stage, film and television productions on both sides of the Atlantic, winning numerous awards. Suffering from multiple sclerosis, the role of Arra was her penultimate performance (she died 13 January 1976 at the age of 53, four months after the episode was broadcast by ATV). Production designer Keith Wilson recalls while she had no difficulty with her craft, she required direction from Ray Austin to understand her abstract and complicated dialogue. Austin recalls her being transported to and from the set via wheelchair. She would tell him "You'd better get this shot, because I'm not going to