The Fourth Doctor and Sarah materialise on the planet Vortis. Following the destruction of the Animus, Vortis has regenerated and the flower forests now once more bloom. A survey team of the winged Menoptera have disappeared while investigating the appearance of strange energy emissions. The only survivor, the wingless Jresta, takes the Doctor and Sarah to a large crystal in a forest clearing, but can’t remember what happened after her team discovered it. A follow-up expedition arrives led by the hostile male Menoptera named Vursus. Vursus looks down on Jresta for her deformity. He orders one of his team to break off part of the crystal for analysis, ignoring the warnings of the Jresta and the travellers. The crystal glows with light. It mesmerises the Menoptera and causes them to fly into