The mysterious visitor at the end of episode four is revealed to be Donald Bruce.  Although he’s Salamander’s head of security, he also seems to have a policeman’s instinct, as he’s willing to listen to the claims of Kent and the Doctor that Salamander is not the universal benefactor he claims to be (although anybody who’s spent time around him surely would have quickly picked up plenty of negative vibes).

Astrid disarms Bruce’s guard and the Doctor attempts to bring Bruce onto their side by handing the gun back to him.  As Bruce says, “you must be a complete fool or very clever.”  The Doctor responds that Bruce will “have to make up your mind to that right away.”  This fairly basic piece of psychology does the trick and Bruce agrees to accompany the Doctor as he attempts to enter the Research Centre.  But as insurance, Astrid and Kent are left behind – under guard.

Meanwhile, Salamander is still underground.  One of the slight problems with the underground scenes is that there’s only three speaking roles – Swann, Colin and Mary (there’s plenty of other people in the scenes, but they’re all just rhubarbing extras who rush around with clipboards, looking busy).  Adam Verney (as Colin) is still machine-gunning his lines, delivering them with an intensity that borders on the manic.  As the character is supposed to be somewhat stir-crazy, it’s a reasonable performance choice – although a little of him does go a long way.  Especially when delivering lines such as “I don’t think it’s right. Just work, sleep, eat, if there’s enough to go round. Like worms under the earth, sightless worms wriggling about without hope, without purpose.”

Mary (Margaret Hickey) has the thankless task of having little to do except react to Colin’s complaints.  Swann (Christopher Burgess) initially seemed also to be a rather uninteresting character, very much Salamander’s yes-man, but events take an unexpected turn when he discovers a fragment of newspaper which was stuck on their new boxes of supplies.  Salamander has told them all that there’s a global war occurring on the surface, and that their work (engineering natural disasters), is vital to the war effort.

But the scrap of newspaper has a report about the sinking of a holiday liner.  How can there be holiday liners in a world at war?  Swann confronts Salamander and it’s the first time that we’ve seen Salamander even slightly shaken.  He quick back-peddles and tells Swann that the war is over, but the survivors are deformed in mind and body.  “They have a kind of society, but it’s evil, corrupt. You don’t think I could expose you to that sort of thing? Think of Mary and the other women.”  Swann insists on going up to the surface with Salamander.  Salamander readily agrees and it’s not hard to understand why – Swann may go up, but he’s not coming down again.

Jamie and Victoria were absent from the previous episode and in the first half of this one were only in a brief shot (as their unconscious bodies were carried past the camera).  Once they’ve woken up, they have to face the tender devotions of Benik.  Milton Johns excels in this scene.  So much is left unsaid, as it’s left to the viewer’s imagination to wonder exactly what Benik would be prepared to do to them.  Jamie tells him that he must have been a nasty little boy, Benik concedes he was, but that he had a very enjoyable childhood.”

But he only gets as far as tugging Victoria’s hair when he’s interrupted by Bruce and (apparently) Salamander.  In order to convince Bruce that Salamander is as corrupt as he believes him to be, the Doctor stays in character for a while – and he’s convincing enough to fool both Jamie and Victoria.  The recovery of this episode allows us to see a few more nice visual touches – as Jamie and Victoria confront the man they believe to be Salamander, the Doctor takes fright and falls off his chair.  He’s then concerned that his friends don’t recognise him, but after miming playing the recorder he’s delighted to find they believe him after all.  Just before this, Letts manages to ramp up the tension as he rapidly cuts between close ups of Hines and Watling as they list some of Salamander’s crimes.

Kent and Astrid manage to distract the guard (thanks to some HP sauce, it appears) and Kent hot-foots it to the Research Station.  He says he’ll have no trouble getting in, since he has a pass (are we supposed to believe that Salamander wouldn’t have had it cancelled by now?!).

At the same time, Astrid is trying to shake off the guard (through a very unconvincing section of forest – alas, it’s too obvious that it’s a studio mock-up) when she hears a cry for help.  She stumbles across a mortally injured Swann, who clearly has come off second best in a tussle with Salamander.  It’s interesting that a few minutes earlier Salamander asked Swann if he was sure he wanted to go right up to the surface – the inference being that if he’d changed his mind, Salamander would have spared his life.   I’m not sure if that was the scripted intention or just how it was played, but it does make the character of Salamander a little more interesting (was he reluctant to kill?  And if so, was it just because he didn’t want to get his own hands dirty?)

As it is, we once again end on a cliff-hanger where neither the Doctor and his friends are in danger.  It’s another atypical ending to an atypical (but far from uninteresting) story.