Herrick was strongly opposed to the Time Lords for what had happened to Minyos, and was hostile towards the Fourth Doctor when he arrived upon the R1C, until Orfe used a pacifier on him. Herrick was in favour of hostilities against the Time Lords and insultingly labelled Orfe a pacifist for not wishing to do so.
Upon their arrival on the planet formed around the P7E, Herrick used a Liebemann laser to blast through the rock. When the guards came after them, he defended his comrades long enough for them to escape. He was taken captive and brought before the Seers who tortured him to gain information about his mission. He told them about the race bank and told them he was a Minyan, much to their disbelief. They set him free, gave him the race bank and returned him to his crew.
However, the Doctor showed them that the cylinders containing the race bank were in fact fission grenades. He had them taken before the Oracle where they exploded. The blast destroyed the planet and flung the R1C into space. The crew, including Herrick, then set off for "Minyos 2", on a journey that would take 370 years. (TV: Underworld)
Behind the scenes
Many of the names and incidents in Underworld were derived from the myth of Jason and the Argonauts. Herrick is an analogue of the Greek hero Heracles (more widely known under his Roman name, Hercules). (INFO: Underworld, DOC: Into the Unknown)