On January 18th, 1977, a crowded commuter train heading for Sydney, came off the track and struck the pillars of an overhead road bridge, crushing part of the train and killing 83 passengers and injuring more than 200 others. This story follows the coronial inquiry into the crash with flash-backs to the main story, and the efforts of the rescuers to free the injured victims.

Dr. Samantha Hill is an earthquake research scientist at a noted university in Washington State. Her alternative theories and her take-charge attitude cause friction with her peers. When the controversial Dr. Hill is ultimately put in charge, she is effectively entrusted with saving the entire population of the West Coast from a series of earthquakes that threaten to permanently fracture the West Coast from the rest of North America.

After surviving a tragedy, paramedic Jenny Challoner struggles with PTSD. Concealing her suffering from husband Chris, friend Alison and daughter Rosie, Jenny's life spirals out of control.