I noted when I reviewed 'Robot' that Terrance Dicks is not my favourite Doctor Who writer. Whilst I stand by this comment in general, I regard 'The Brain of Morbius' as the highlight of his Doctor Who career, and the success of this story is perhaps therefore due to the fact that Robin Bland is not, in fact, Terrance Dicks, but Terrance Dicks heavily script-edited by Robert Holmes.
'The Brain of Morbius' is of course heavily influenced by Frankenstein, and in many respects feels like a homage to Hammer Horror. This results in a distinctly gothic feel to the story, which is unusually horrific even for this period in the series' history. The opening scene of Kriz the Mutt being beheaded by Condo sets the tone, and this is followed by Kriz's twitching head being wired up by Solon, the discover of the headless but obviously living Morbius monster at the end of Episode Two, the revelation of Morbius's brain floating in a tank, Condo's bloody and graphic shooting at the hands of Solon, and the grotesque sight of Solon gingerly cradling Morbius's brain in Episode Three. In addition to which we have the Sisterhood carrying out human sacrifice. This macabre atmosphere typifies 'The Brain of Morbius' and is crucial to its success; the entire story is set on an alien planet, but it could just as easily be set in a Hammer Horror version of Transylvania, with a gothic castle atop a bleak and rocky mountain, a mad scientist, a hunchbacked manservant, and a local coven of witches in the form of Sisterhood.
The actual plot of 'The Brain of Morbius' is very simple; Solon wants the Doctor's head in order to house Morbius's brain and the Doctor is understandably reluctant to surrender it. Solon thus spends most of the first three episodes chasing after the Doctor, whilst he is alternately hindered and helped by the Sisterhood of Karn. By Episode Four, Morbius once more has a body and the emphasis changes as the Doctor, Sarah and the Sisterhood strive to destroy him. Whilst this plot is sound enough in its own right, what really makes it work is the exemplary characterisation and acting. Philip Madoc almost steals the show as Solon, playing a mad scientist without succumbing to the temptation to go over the top. Whilst Solon is undoubtedly insane, Madoc plays him with such pathos that we see numerous different aspects of his personality. Most overwhelming of course is his obsession with Morbius, and obsession, which has, as he himself notes in Episode Three, forced him to spend years in desperately lonely isolation. His absolute devotion to Morbius drives him completely, everything he does motivated purely by his need to complete his work. As played by Madoc he is nervous and twitchy, impatient to find a head for Morbius's brain, and this results in an air of wild eyed but restrained of mania. But Solon displays other attributes too; he's short-tempered, most notably with Condo, and when enraged he resorts to physical violence, cuffing his servant around the head and eventually shooting him. But he's also largely a coward, and it is thus his obsession with Morbius alone that drives him to desperate measures. When Solon realsies that the Sisterhood have "rescued" the Doctor, he rants and raves, describing them as "a squalid brood of harpies", and when he reaches their temple and discovers that they intend to sacrifice the Doctor, his desperation to obtain the Doctor's head drives him to dare to interrupt the ceremony. However, once his adrenaline rush wears off, he realises his folly and panics; when he pleads with Maren for the Doctor's head he babbles in obvious fear, offering Condo instead out of shear desperation. Indeed, his desperation is such that in addition to endangering himself by risking the wrath of the Sisterhood he comes close to blurting out his reasons for wanting the Doctor's head, thus also endangering Morbius. In addition to his humiliating failure, he also pushes Condo too far, resulting in his near death back at his castle, as Condo angrily pulls a knife on him. With little other option, he is then forced to offer Condo his other arm back, a promise he has no intention of keeping; this further complicates matters for him, as he needs to find a way of stalling Condo as a result.
It is this deeply flawed persona that makes Solon work so well as a character, and there are other examples throughout. In Episode One, when the Doctor and Sarah first arrive, Solon is at his most charming as he grasps the opportunity presenting itself, but despite the effort he makes, his desperate obsession means that his charm barely covers his grotesque intentions for the Doctor's head and he comes across as decidedly creepy, as Sarah very obviously notices. Ironically, it seems that despite Solon's total devotion to Morbius, Morbius himself has little regard for Solon; Morbius's paranoia and rage whilst trapped in his tank is understandable, but it is worth noting than when he is finally properly installed in his new body, he casually discards the corpse of the newly deceased Solon, despite the fact that he has Solon to thank for his resurrection. It is perhaps fitting that Solon dies just as he completes his life's work.
Morbius too is well characterised. Whilst trapped in his tank, he sounds desperate and paranoid, and Michael Spice's voice conveys some of the horror of his situation very well. Once Morbius is released however, he changes, becoming both confident and arrogant as he confronts the Doctor in Episode Four. For all that the Doctor and Maren describe the threat posed by Morbius, most of 'The Brain of Morbius' essentially revolves around a very localized threat to the Doctor and Sarah; nevertheless during the brief period in which Morbius is housed in his new body and is lucid, Spice manages to create sufficient charisma for Morbius to make it believable that he could rouse an army to threaten the entire galaxy. Appropriately, Morbius's confidence proves his undoing, as he accepts the Doctor's challenge of a mindbending contest, and pays the price. And the sight of Morbius's brain almost literally blowing a fuse is strangely disturbing as his brain case fills with smoke.
Contributing to the atmosphere of 'The Brain of Morbius' is the Sisterhood of Karn, who despite ending up on the same side as the Doctor in the fight against Morbius is by no means particularly friendly. Whereas Solon is motivated by his obsession with Morbius to commit murder, the Sisterhood are motivated by their jealous possession of the Elixir of Life to commit atrocities that are at least as bad. So paranoid are they about guarding the Elixir and their Sacred Flame that they drag ship after ship to its doom, regardless of whether those ships are headed for Karn or of what their occupants intend. On first discovering the Doctor's presence on Karn, Maren assumes the worst and decides to burn him alive; in short, the Doctor's only allies on Karn are not nice people, and this adds to the general sense of danger in 'The Brain of Morbius'. As with Michael Spice as Morbius and Philip Madoc as Solon, Cynthia Grenville as Maren puts in a great performance, alternating between imperious and unforgiving in the first two episodes, and later showing a more vulnerable side, as the Doctor's criticisms of the unchanging Sisterhood hit home and she shows the weariness one might expect after centuries of stagnation. The Doctor's effect on the Sisterhood is quite profound, as his constant gentle mockery gradually has an impact not only on Maren but also on Ohica. By the end of the story there is a suggestion that the long-unchanged Sisterhood has been affected not only by Morbius's brief return, but also by the Doctor, and that there is hope that they will, if nothing else, at least stop hijacking passing space travellers and killing strangers without discrimination.
By this point in the season, it almost goes without saying that Tom Baker and Elizabeth Sladen are excellent, but it is worth noting that 'The Brain of Morbius' is a particularly good story for Sarah. Unusually, all three cliffhangers revolve around Sarah instead of the Doctor, and of course she also gets blinded, a situation with allows Sladen to shine as she conveys a sense of barely restrained panic. Sarah is also frequently terrified here, encountering headless monsters and being forced to assist Solon in his brain transplant operation in Episode Four, unable to see and under threat of death. When Condo grabs her by her hair in Episode Three she is again clearly terrified, this giving way to revulsion as Condo shyly tells he likes her. When he saves her from the monster in Episode Four but is killed in the process, she sounds suitably guilty, as she struggles with the fact that Solon's hulking manservant has saved her life at the cost of his own. Of all the supporting characters in 'The Brain of Morbius', Colin Fay's Condo is arguably the most sympathetic; whereas Solon commits atrocities out of obsession and the Sisterhood commit murder out of jealous possessiveness, Condo kills (at least as far as the audience knows) because of Solon's hold over him; Condo wants his arm back. This doesn't excuse him, but in a story filled with characters who are on very dubious moral ground, Condo's actions are marginally more justifiable. His attraction to Sarah also adds to his character, in an amusing nod to The Hunchback of Notre Dame. The Doctor also shines, on the one hand at his wittiest when dealing with the Sisterhood (to Maren's obvious annoyance), on the other at his most intense when dealing with Morbius and Solon; his decision to resort to using cyanide gas to try and stop Solon is testament to how dangerous he considers Morbius and shows him at his most committed.
Production wise, 'The Brain of Morbius' is exemplary. It's very well directed, the score is marvelously evocative, and the sets are superb, especially Solon's castle. Also worth mentioning is the rocky landscape of Karn, which is one of the series better rocky landscape sets. The costumes are also very effective, from the elaborate flame-decorated robes of the Sisterhood to Solon's understated tweedy suit. The Morbius monster is particularly impressive, managing to look like it is made of alien body parts whilst still successfully looking like a piecemeal abomination rather than an actual alien creature. Overall, 'The Brain of Morbius' is a highly effective if unusual story, and after the dreadful 'The Android Invasion' it marks a return to the generally high quality of the season as a whole. A level of quality that will be maintained for the season finale