Doctor Who: Match of the Day

There were the contracts, the agents, the local sponsors, the pay-per-view broadcasts, the independent verification of results, the laws which made murder legal in carefully defined circumstances... It had taken a long time for the system of freelance duelists to be established, and an even longer time to develop the league of interplanetary superstars the others fought to reach and to challenge. And just when it was all working satisfactorily and profitably someone or something started interfering with the set up. Famous fighters died in private duels. Up-and-coming professional fighters began to fall victim to casual, one-time challengers - the sort of psychos and testosterone-addled drunks who would themselves be expected to die quickly and routinely. When Leela is challenged to a duel to the death, the Doctor realizes that there is more to the situation than simple murder and mayhem. But before he can sort it out, he needs to save his client - Leela. How long can she survive on a planet where not to kill is an offense punishable by death?