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.

Firebombers takes a comprehensive look into this significant and controversial period in Welsh history. Episode one begins with the first arson attacks in December 1979 – on two second homes in Pembrokeshire and two in north Wales. Three more are attacked the very next day in Blaenau Ffestiniog, with a total of 17 homes destroyed across west and north Wales within six weeks.

In response to the attacks, Dyfed-Powys and North Wales Police set up Firesquad, a specialist team of officers tasked with catching the firebombers. A BBC investigation for the Nationwide programme discovered several secret groups claiming responsibility for the attacks.

By 1986, the arson campaign would be identified as being by a secret organisation known as Meibion Glyndŵr, after letters claiming responsibility were sent to the media. Despite police efforts, whoever was masterminding the campaign seemed to have evaded capture.

Archive footage is combined with new interviews with people from very different perspectives who were involved at the time. They include the police who investigated the cases, victims whose properties were burned down, journalists who covered the story, and people who were arrested.