After an encounter with the Master, an airline stewardess named Tegan Jovanka becomes an unwitting stowaway aboard the TARDIS as it travels to the planet Logopolis. There, the Doctor discovers that the Master's interference with the Logopolitans' advanced mathematics has unleashed a wave of entropy which threatens to consume the entire universe.

Rush was an Australian television series produced by the Australian Broadcasting Corporation between 1974 and 1976. The first 13 episodes were produced in 1974 and filmed in black and white. In 1976, 13 more episodes were produced, in colour, in conjunction with French production company Antenne 2. Each series featured a different cast with the exception of John Waters.