Firebombers

It’s 1979, and a campaign of arson has begun in Wales. The targets are English-owned second homes that the attackers say are destroying Welsh culture. Over the next ten-plus years, well over 200 homes and businesses will be attacked, in Wales and beyond.

It's 1986, and the arson group have ramped up their attacks, taking the firebombing campaign over the border into England. The government enlist the help of MI5 to catch those responsible.