Hinchcliffe, together with script editor Robert Holmes, ushered in a change in tone for the series, which became darker and more adult than previously, with a gothic atmosphere influenced by the horror films produced by Hammer Film Productions. This horror influence is especially evident in serials like "Planet of Evil", "Pyramids of Mars", "The Brain of Morbius", "The Hand of Fear" and "The Talons of Weng-Chiang", all of which have content which directly recalls well known horror novels and movies. Hinchcliffe also aspired to give the programme a more literary feel with a stronger science fiction basis. Working closely with Holmes, Hinchcliffe tried to "tighten the whole storytelling up a bit and pay more attention to the design", but he conceded that it was improved "in some stories more than others". As part of the effort to "tighten" the storytelling they were permitted to reduce the number of six-parters to just one a season (the previous team of Barry Letts and Terrance Dicks made three six-parters per season in their last three seasons).