Disaster will strike for Chris, Sophie Ramsay, Andrew Robinson, Tash Williams, Summer Hoyland and Ed Lee in the terrifying road accident.
Talking through the chain of events, Mason told TV Week that the teens are on the way to a concert when they discover that Sophie Ramsay has secured a ride by hiding in the boot. Chris then agrees to let her sit on Summer's knee as the journey continues.
Mason commented: "Chris really is a pretty sensible, straightforward kind of guy who knows the rules - his morals are good. But he gets talked into overloading the car by letting Sophie get in with them.
"He wants to please his friends and make sure everyone's happy - and it doesn't help that the whole group use a bit of peer pressure to convince him. The others just don't see any danger in what they're doing."
It was recently confirmed that with too many passengers in the vehicle, a heated argument will lead to driver Chris getting distracted and swerving off the road. The row is between Andrew and Tash over their gambling app.
Neighbours fans in Australia will see the storyline begin next Monday (August 20). The scenes air in the UK from September 17.
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Watch the official promo for the car crash episodes below: