Seven seconds is all it took. Seven horrifying seconds to end four young lives. Kate Goodchild. Luke Dorsett. Roozi Araghi. Cindy Low. All killed when their raft tipped over on the Thunder River Rapids ride at Dreamworld nearly two years ago. It was a tragedy that profoundly shocked the nation. But, for one woman, the horror of that day is unbearable. Kim Dorsett was on holiday on the Gold Coast with her family. Both her children, Luke and Kate, died in the accident. For the first time on Sunday Night, Kim’s search for the truth about what happened that day – and how, amidst all the chaos, an act of courage saved the life of her 12-year-old granddaughter. Alex Cullen reports.