Lieutenant Dawson Walking Bear, who was first featured in Star Trek, The Animated Series, is featured in this episode where he begins to see visions of a wolf roaming the USS Enterprise corridors. Dr. McCoy has no explanation medically for Walking Bear's hallucinations but says there may be a correlation between his and his mother's 30th birthday who was lost on a deep space scouting mission. The suspense heightens when Walking Bear is confronted by the unexplained on his next away mission. Another 'come to life' character from the animated series is the cat-like alien, M'Ress.