Alerted by the Brigadier, the Doctor and Leela track a powerful object to a remote Scottish isle – and discover that time is not on their side…

This four-part story is the latest to come from the collaboration between Big Finish and Philip Hinchchliffe, producer of some of the best Doctor Who stories from the classic era (in my opinion – but I was exactly the right age when they were first broadcast!). Once again working with writer Marc Platt, Hinchcliffe has slotted a story neatly into the gap between The Talons of Weng-Chiang and his successor’s first story Horror of Fang Rock.

They’ve provided both Tom Baker and Louise Jameson with plenty of strong material in a story that you do need to concentrate on to follow – the end of episode 1 in particular is more than a little confusing on first hearing – with new elements constantly being added. Jameson in particular seems to be having a lot of fun – listening to her ululation on the Sevateem war cry can’t fail to bring a smile to your face.

Director Ken Bentley’s assembled a formidable cast who treat the material with absolute sincerity and there are some very effective soundscapes courtesy of Kelly Ellis. Jamie Robertson’s music often veers towards the Dudley Simpson-esque, although ironically, I suspect a more Geoffrey Burgon-influenced score would have been more appropriate for this, tying it in further with Terror of the Zygons.

Verdict: Definitely feeling appropriate for the period of Who it’s emulating, this is an enjoyable, if perhaps slightly overconvoluted, story. 8/10

Paul Simpson