Although incredibly intelligent amongst his kind, Thermoman is unfamiliar with human life, which not only leads others to consider him dim-witted and idiotic, but also causes problems due to his many misunderstandings.

The main role of Thermoman was portrayed by Ardal O'Hanlon up until 2005, before he was replaced by James Dreyfus for the final series.

The cast itself remained largely unchanged throughout its broadcast history, and included Emily Joyce, Lill Roughley, Tim Wylton, Lou Hirsch, Hugh Dennis, Geraldine McNulty, and Philip Whitchurch.

[5] The series focuses on the life of George Sunday, a man who comes off as idiotic, but who in reality is a superhero from the planet Ultron known as "Thermoman", who serves to safeguard humanity and the Earth, and Janet Dawkins, a British nurse who works at a local surgery in the London town of Northolt, whom George falls in love with after saving her life.

The series focuses on the couple's efforts to cope with numerous problems that occur to them during their relationship, including dealing with Janet's obnoxius parents and the self-centered doctor whom she works for, and George's many misunderstandings of human culture, societial values and traits.