This final, six-part, instalment of the "Key to Time" series splits quite neatly into two stories, really. The first sees our travelling Time Lord (Tom Baker) and his colleague "Romana" (Mary Tamm) arrive on the planet of "Atrios" right in the middle of their war with the neighbouring "Zeos". Thus far it's proved a bit of a stalemate, but the "Marshal" (John Woodvine) reckons he has a plan that will prove decisive, despite the more pacifist hopes of his princess "Astra" (Lalla Ward). Meantime, though, the "Doctor" begins to wonder if someone else isn't pulling the strings here and when they stumble upon a trans-mat beam they are introduced to the maniacal "Shadow" (William Squire) who rather worryingly knows more than he should about the closing stages of their quest. The "Key to Time" theme was always a rather weakly exploited one, and this denouement didn't really catch fire either. It's all adequate storytelling but there's just too much over-acting and not enough action until the final episode when a combination of factors and some participation from "K9" (and his laser gun) livened it up a bit. I usually felt four parts did the job with these, any more and they were too strung out - and this rather proves that theory. Time for a new assistant, too, I think.