This chapter offers a possible worlds theory (e.g. Ryan 1991, Bell 2010) approach to metalepsis and, through its application to digital fiction in particular, shows how possible worlds theory can offer as a transmedial approach (Ryan 2005) to this ontologically transgressive fictional device (cf. Bell and Alber 2012). In narrative theory, a metalepsis refers to a point in a text when an entity appears to move between narrative levels such as when a character talks to the narrator of the text s/he is in or when an author becomes a character in the novel s/he is writing (Genette 1980, Fludernik 2003). This chapter argues that conceptualising metalepses as transgressions between worlds as opposed to the more abstract concept of diegetic levels...