Nick and Adam attempt to rescue a young girl from a flooded stormwater drain. Nick sends Adam for help while he holds the girl to stop her from being dragged away. However, Adam is delayed by a crisis involving the girl's sister and, worn down by exhaustion, Nick loses his grip on the girl.
This episode is revealed in flashbacks when Nick and Adam return to the station and their colleagues piece together the story. Nick vents his frustration on Adam. Eventually the news comes in that one of the sisters lived and the other died. Nick and Adam start the healing process by going to inform the parents of their child's death.
Source:
Australian Television Information Archive