Release Message:  The Doctor (Tom Baker) learns that Styre has been experimenting on the Galsec crewmembers to pave the way for a Sontaran invasion of Earth.

Description:  The Doctor learns that Styre has been experimenting on the Galsec crewmembers to pave the way for a Sontaran invasion of Earth and decides the only way to halt his plans is to challenge him to a duel.