The Barn Fire (2000)
Andy Sugden set fire to a barn so his adoptive Dad could claim the insurance money. However, he accidentally killed his adoptive Mum, who was in the barn finishing her affair with toyboy, Richie Carter. Carter survived and made a brief return to the soap in 2007 for the 35th anniversary of Emmerdale, when Andy's little sister, Victoria tracked him down to get answers about her mother's death. This led to Victoria setting fire to a cottage and the truth about the night seven years before, coming out. (See "Sugden House Fire" section below). Andy was therefore jailed which changed him and caused him to domestically abuse his wife, Jo, on his release in 2008.
Read more about this topic: Major Emmerdale Storylines