Sarah throws a Wollongong High School reunion to show off her blossoming new garden, but the success of her old school mates only deepens her crisis of self-worth. Rachel invites a bunch of randoms who turn the party to chaos.

The gang travel 300 million years back in time using Lucas's time machine, where Sarah tries to rescue the Australian megafauna from an impending comet using skills she's learnt from a self-help guide.