Closing in on their $1M season target, the Cheals finally get two agitators up and running, doubling opal production -- but then they've got to face off against veteran opal dealer Sonja Trifunovic in an attempted $100,000 sale. The Blacklighters' team leader, Mark I'Anson, is severely injured and hospitalized in a mining accident, forcing Paul and John to work overtime on two separate claims to scrape together enough opal to survive the week. The Mooka Boys' season from hell continues -- on their last load of fuel, the sole working digger overheats and dumps diesel, forcing Matt and his brother Cozza on a night mission that unearths unusual glowing yellow rocks.