Denise McGregor was last seen near her home in Pascoe Vale on 20 March 1978. Within minutes, she had disappeared. 

What happened in the time between her last sighting and the search that followed remains critical to understanding the case.

Before any explanation can be taken seriously, it must fit the evidence — and the limits of what can still be known.

In this episode, plausible scenarios are tested against the constraints established so far: time, distance, opportunity, risk, and the realities of surviving evidence from 1978.

This is not an episode about identifying suspects or assigning guilt. It is an exercise in feasibility — examining which explanations can be ruled out, which remain possible, and why certainty has remained elusive.

Understanding these constraints is essential. Every explanation must pass through them.

This episode sets out what any account must satisfy — and why some begin to fail when measured against what is known.