Pik Solus was a New Alzarian. He was part of a mission headed by Decider Lana Merrion to Alzarius to search for Marshmen. He questioned the Fifth Doctor and Tegan Jovanka who knew of their past.
In reality, Solus and a Higari named Drell planned to kill Merrion because she diverted a tidal wave which killed his sister and eight hundred Higari. He later destroyed the expeditions spaceship.
He later found Vislor Turlough, Nyssa, Yan Fara and Drell. He had Drell kill Fara and took Turlough and Nyssa prisoner. He and Drell followed Merrion and the survivors to a cave system and tied up Nyssa and Turlough and placed several riverfruit full of Alzarian spiders to kill them.
He and Drell later managed to find Merrion and captured her. After Merrion told them what had really happened about the tidal wave, Solus shot Drell fatally but, before he could kill Merrion, he was stopped by Turlough and the Marshmen. He later managed to escape in Fara's spaceship, taking a vital component of the TARDIS with him. (AUDIO: Mistfall)
He crashed landed on Isenfel and was cared for by Balancer Skaarsgard, but his injuries eventually proved too severe and he died before the TARDIS arrived. (AUDIO: Equilibrium)