buzzword

Can anyone tell me anything about the underscore used in the episodes where Belle was dying? Has it been used before or was it specifically composed for this storyline? Can I download it anywhere?

I'm looking for the episode number of an episode towards the end of 2008. In this ep Kirsty and Miles had a really nice scene in the caravan park at night, and there was a really nice underscore being played. Anyone know what episode this is?