Sivertsen has produced and animated a number of short animations since the early 1980s and since 1990 in his own company AnimaThorFilm. He has his work base in Nord-Trøndelag, where he works with advertising and short films, both digital and analogue. Zwish! is a character animation that also represented a timely celebration of the animated film inevitably not only synonymous with 'children's film'.
Meet Joel Goodson, an industrious, college-bound 17-year-old and a responsible, trustworthy son. However, when his parents go away and leave him home alone in the wealthy Chicago suburbs with the Porsche at his disposal he quickly decides he has been good for too long and it is time to enjoy himself.
The film portrays a fictional nuclear war between NATO forces and the Warsaw Pact that rapidly escalates into a full scale exchange between the United States and the Soviet Union, focusing on the residents of Lawrence, Kansas, and Kansas City, Missouri, as well as several family farms situated next to nearby nuclear missile silos.
Based on the real-life Richard Speck murders, amoral, nearly psychotic killer Warren Stacey (Gene Davis) is a serial killer who has murdered a number of women; he stabs them while they are naked to minimize leaving any physical evidence.