Vicki awakes on board the UK-201 – before its crash onto the surface of the planet Dido. Can she somehow prevent the tragedy she knows will occur?

The early years of Doctor Who experimented with “sideways” stories, and occasionally played with time travel in very usual ways – look, for example, at The Space Museum, where the travellers “jump a time track” and see their own futures. Jonathan Morris’ fascinating four-parter is of that ilk, but centres on Vicki arriving back in her own past, with Steven somehow along for the ride. If you enjoyed Star Trek: Deep Space 9’s The Visitor, chances are you’ll enjoy this, although Morris doesn’t keep things as linear; Vicki and Steven’s attempts to deal with the situation lead to more problems, and it’s an opportunity to get to know a lot more about the young orphan.

This is a tour de force by Maureen O’Brien who has to portray Vicki at many different stages, while Peter Purves’ Steven is a constant throughout. The Doctor’s presence is critical, even when the focus is firmly on his companions (to the extent that at times this does feel rather more like a Companion Chronicle than an Early Adventure – Hartnell would have had the chance for a good trip to the Riviera for his involvement in much of this).

Director Lisa Bowerman has, as ever, brought together a strong cast to back up the two principals, with Michael Lumsden as Vicki’s father and Stephen Fewell’s Jeran Dalton particularly affecting, while Toby Hrycek-Robinson’s music and sound design are essential to selling the subtle differences within the piece.

Verdict: An unusual story that will reverberate long after you’ve finished listening. 9/10

Paul Simpson