In The Curse of Fenric Ace told The Doctor, "Professor, I'm not a little girl" shortly before creating a distraction with a nice little temptress routine. Here Ace goes the whole nine yards and beds a member of the Mendeb bourgeoisie named Kedin Ashar. A first for me. My impression is that Ace beds quite a few gentlemen in the NAs but this is the first time she has done so in a PDA. Not a little girl indeed.
The problem starts when the TARDIS brings Second Doctor and Jamie to the Mendeb system but find the heat oppressive and no obvious way to interfere with another civilization. The Doctor vows to return but Jamie is not at all confident that the Time Lord will actually remember to do so. To help jog The Doctor's memory in the future, Jamie grabs a souvenir. Unfortunately the tchotchke ends up being a vital component to a communications system. Many years later Ace discovers the circuit and The Doctor's memory is jolted. They return to the Mendeb system in hope of returning the part, restoring communication between the inhabitants of Mendeb Two and Mendeb Three, and having a happy ending.
Despite having a time machine, nothing could ever go so smoothly. The TARDIS lands on a space station which resides in orbit between Mendeb Two and Three which were settled by the TAM Corporation many centuries ago. The company abandoned the planets and took most of their precious technology with them leaving the people behind to start anew. Ace is keen on adventure and has The Doctor leave her there to explore while he continues to Mendeb Two. Unbeknownst to our intrepid heroes, the inhabitants of Mendeb Three are quite technologically advanced in contrast to their brethren on Two. The aforementioned Kedin Ashar is Mendeb's Alfred Krupp, inventing and manufacturing arms for the scheming and treacherous Duke Vethran.
Things have gotten to the point where there are no checks on Vethran's ambitions. Ashar plots a putsch and enters the slave trade in order to fund his rebellion. He is kidnapping the peaceful folks on Mendeb Two, giving them a drug called SS 10 which strips them of their volition, and pawning them off to the petty nobility of Mendeb Three.
Ashar does his work from the space station where he runs into Ace who is almost immediately smitten with him. While he is also taken with her, he pines for his love, Tevana, who is being held in seclusion by Vethran as insurance. But Ace is able to operate some of the station's technology that has escaped the abilities of Ashar and his compatriots. The afterglow of their night at the horizontal disco wears off quickly once Ace figures out that the man she bedded is involved in human trafficking. Ashar has her drugged and sent to Mended Three where she will at least be safe, if a mindless slave.
Meanwhile The Doctor befriends Bep-Wor, the lone survivor from a village that was destroyed and whose inhabitants were forced into slavery. Bep-Wor follows The Doctor in hopes of being reunited with his love, Kia-Ga. The Doctor ends up being this Spartacus figure leading a rag-tag group of people against the slave masters of Mendeb Three while Ace is a slave that ends up in the service of Vethran.
There's no mystery here for The Doctor and Ace to solve. Instead we have one of those stories where The Doctor and Ace find themselves between two parties in conflict. I thought the opening gambit with Jamie snagging a vital bit of circuitry to be pretty lame. You'd think Jamie would know better than to screw with things wires and "flickering wee lights". That The Doctor and Ace are separated for most of the story may or may not appeal to any given reader. On the one hand, it deprives us of Doctor-companion banter. But on the other it gives Ace to prove her mettle instead of being dependent on The Doctor. (And it gives her time for some carnal indulgences.) Unfortunately she spends a lot of time under the influence of an SS 10-like drug, essentially out of commission until she can be the hero at the last minute.
I liked the meta love triangle here. Ashar works to rescue Tevana, Bep-Wor seeks Kia-Ga, and The Doctor tries to get back to Ace. Of the three, only the last comes to something akin to a happy ending. Tevana and Kia-Ga had both been dosed with SS 10 the effect of which The Doctor finds to be inalterable. Bep-Wor (what's with these hyphenated names for the people on Two?) ends his grief by ending his own life while Ashar sinks into the depths of perdition. Ace decides to stay and start a new life in the Mendeb system but is dissuaded by Ashar who, in the end, concludes that the only choice left is to simply carry on.
This ending is bleak for more than just the Mendebians. Sure, Ace escapes becoming an SS 10 zombie but all is not well with her and The Doctor. She wants independence. She needs a break from her travels. For his part, The Doctor seems to have a touch of melancholia. He is unable to reverse the effects of SS 10, for one thing. But there is more to it than that. Ashar tells Ace in rejecting her offer to stay, "He needs you, Ace. He can't function without you. And, from what you tell me, he has a great burden to carry and much to do." Perhaps it is an angst that only Time Lords can understand.