After graduating she worked for the French director Gilles Bourdos (Afterwards, Renoir) for a year. In 2009, Mannheimer began working on The Ceremony, a documentary film featuring French author and dominatrix Catherine Robbe-Grillet and her Inner Circle. The Contract, her debut film, constituted the first part of The Ceremony. The Ceremony premiered at CPH:DOX 2014 competing for the NORDIC:DOX awards and the Nordic Awards at Göteborg Film Festival as well as got selected at SXSW in the Spring 2015. The Swedish theatrical release was February 2015 and to a strong reception amongst critics and press. Mannheimer’s second feature Mating premiered this year at Göteborg Film Festival, it was nominated for the Best Nordic Doc’s Award as well as the Nordic:Dox award at CPH:DOX. Mating had a wide theatrical release in Sweden and premiered on the 29th of March 2019.