Blood is spilled for real in Part Two of "The Stones of Blood" as the identity of the Cailleach, the ancient hag still worshipped by modern-day Druids, is revealed, but for disciples De Vries (Nicholas McArdle) and Martha (Elaine Ives-Cameron), the price of devotion proves too high while Romana, clinging precariously from a towering cliff, nevertheless proves wary of the Doctor who rescues her from a fatal plunge.
David Fisher's efficient script advances the narrative, launched as the two Time Lords land on Earth in contemporary Cornwall in their quest for the third segment to the Key to Time, and ups the ante in terms of intrigue and peril. Following his own near-miss on the sacrificial altar, saved only by the timely arrival of archaeologist Emilia Rumford (Beatrix Lehmann), the Doctor, with K9 in tow (at one point literally as the mechanical dog gets a camouflaged turbo-boost), pays a call on De Vries only to find mineral mayhem has torn through his baronial hall.
Meanwhile, Romana, helping Professor Rumford do research at the cottage of Emilia's assistant Vivien Fay (Susan Engel), discovers that ownership of the lands containing both De Vries's hall and the Nine Travelers, the stone circle Emilia and Vivien have been surveying, has always been in the hands of women, at least until recently. She and Emilia head over to the hall---only to find that the mayhem visited upon De Vries and Martha has taken its toll on the Doctor and especially K9, who is left clinging to electronic life after battling an Ogri, an ambulant stone monolith serving the Cailleach.
While Romana returns K9 to the TARDIS to effect repairs on him, the Doctor and Emilia discover a secret passage in the hall before making an even more shocking find in the hidden chamber that proves Vivien is much more than an assistant---which Romana also discovers when she returns to the hall and is waylaid at the stone circle by Vivien, decked out in much different plumage than previously, who casts Romana into another cliffhanger to close Part Two.
In this transitional episode, Lehmann develops Emilia into a full-fledged character---a colorful one, to tell from the police truncheon she takes with her to De Vries's hall that got her arrested during a visit to New York---while Engel's Vivien is by necessity circumspect as Engel plays coy, even when Romana encounters Vivien in her rather obvious avian attire. As is typical for classic-era "Doctor Who," the Ogri, despite being animated by the consumption of human blood, is another dubious monster sure to look even more dubious before "The Stones of Blood" (that cat now fully out of the bag) runs its course.
Sure pacing and shot-framing by director Darrol Blake keep Fisher's expository narrative flowing as Tom Baker and Mary Tamm, despite being kept apart for much of the episode, demonstrate that they've fallen into a lively rhythm that displays the subtleties of a strengthening relationship, even when Romana still maintains her suspicions during her rescue from the previous cliffhanger. Laying the pipe needed to bring "The Stones of Blood" to its conclusion, Part Two keeps its blood flowing to sustain the momentum.
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