Errant Heart takes place in a fictional 1940's Europe (sans Hitler) and follows the exploits of a young painter, Lira Moretti. As she leaves home in order to establish herself as artist in the cosmopolitan mainland city of San Moritz, she has a bizarre encounter with a street urchin which leaves her with a gap in her memory.

Unsure of how she arrived at her final destination of Mrs. Hinze's boarding house, she runs afoul of her granddaughter, Elena. Accused of being a disruptive drunkard, Lira does her best to salvage the scenario and surprisingly, ends up on the good side of Mrs. Hinze.

As she settles in to life in San Moritz, Lira struggles to choose between starting her painting career or following up on the bizarre circumstances that she encountered upon her arrival. Eventually, after having apparently been followed by the street urchin, Salima draws Lira deeper into an extraordinary world where the passage of time takes on new meaning—a world which runs parallel but utterly unseen to the eyes of the banal.