|I like this image 'cause it makes the mansion look like|
A SPAAAACE MANSION.
We'll go into that setting, I suppose. Victorian England, 1883. Itself a haunted time with a lot of gross old-fashioned values. There's some weird shit afoot in the halls of a mansion called Gabriel Chase, and the Doctor's got an ulterior motive for popping back here. His companion Ace was here before, in 1983. She felt a presence in this place, something bad. The Doctor has brought her here, in his role as professor and teacher, to help her overcome her fear... but he's done so without telling her. At the end of Part 1 Ace is basically furious with him for bringing her back to such an awful place. He'll do something similar a story later in The Curse Of Fenric, bringing Ace to a place that confronts her with her past and makes her grow stronger from the encounter... but Gabriel Chase is a bad place. The dark forces that will leave the psychic impression that Ace encounters in 1983 are alive and well in 1883, and up to no good. There's musings on evolution and a malicious plot carried out by a Josiah Samuel Smith which involves lots of brainwashing, de-evolving folks, and aspirations of killing Queen Victoria and taking over the British Empire. He's some sort of creature which keeps evolving and changing, and eventually evolves into a Victorian "gentleman", warts and all. Too effective, almost. Judging by his "rule" of Gabriel Chase, we can guess as to how well a British Empire under his command would go. All these plans are scuttled by the stone ship in the basement, and the mysterious Control which lurks within, a hissing female voice. The Bertha Mason to Josiah's Mr. Rochester. Control's restraints are social as well as literal, and her quest to gain her freedom and become a "ladylike" will bear fruit... but it's the other being in the basement which is the real threat.
The titular Light emerges for the final episode, a being of thought which seeks to categorize all life on Earth but is thwarted by the fact that it keeps evolving and changing. Material biological progress pisses him off, and his actor has an interesting way of portraying it. At first Light speaks in this high, airy voice... but once he gets angrier he lowers it, and it's like he's showing his true colors. With no regard for human life, he dismantles maids to study them and turns people to stone to keep them from changing in any minute way. The Doctor foils Light by citing the gaps in his catalogue; all of them imaginary creatures. No gryphons, dragons, or bandersnatches. Ideas are what beat Light in the end. Or is it creativity and constant change? Whatever it is, Light is done. Control is in charge now, and Josiah is the subservient one. So it is that the stone ship departs for a more enlightened age in space... but the echo of Light and all of the malice within is left within Gabriel Chase. Ace has faced her fear, and now knows exactly what presence she felt in 1983. Her response is wishing she'd blown the house up instead of just burning it. Ghost Light's great. It's far more complex and heady than my surface-level writeup gives it credit for. You could write a book about this story. OH WAIT SOMEONE DID HOLY SHIT. There are some good spooky scenes, lots of thunder crackling overhead within the scary mansion, and it's generally a good 75 minutes. It might confuse the hell out of you at first, but stick with it. It ain't goddamn Ulysses, it's just Doctor Who... and we know that Doctor Who can be spooky. Besides, if you give it a go you might be more inclined to check out the McCoy years. That'd make me happy 'cause I love this period of the show. That's all there is to say on that. File THAT in your records, Light.