 In "Boom Town", the Ninth Doctor refers to the Rift in the plural, indicating that there are others elsewhere.In series 3 episode "The Sound of Drums" (2007), the Master (John Simm) also refers to the Doctor sealing the rift at the heart of the Medusa Cascade, deep in space.The Daleks later planned to make use of this rift in spreading their Reality Bomb ("Journey's End", 2008).