That Hideous Strength by C.S. Lewis
I think the reason this book fails in the end is that the active agency producing the result is too diffused. You can say somewhat precisely that the ending is achieved by the concerted work of a company. But you can say more precisely that the ending is achieved by a peripheral character, that arises like a deus ex machina to deliver our two protagonists from their plight.
Lewis was good at making Out of the Silent Planet work without a climactic confrontation. His character is passive, but his story is complete: he survives, he grows, his choices have a direct bearing on the outcome. In Perelandra, Lewis has a quest of sorts, an epic battle, and then ends the story perfectly, having set everything up from the beginning. Those two stories have plots that feed into their conclusions. The problem in That Hideous Strength is that our main characters don’t themselves bring about the outcome. I don’t think the plot is coherent in that it reaches beyond our two main characters and in the end depends on a third. It is a coherent plot in the sense of ideas and events, but isn’t the outworking of the character’s choices alone, and that I think scatters the ending.
Still, it is a good book, with a lot to think about, a lot of interesting things imagined for us, a lot of good characters playing out their beliefs and ideas, and excellently imagined scenes and situations. It is an ingenious ending, even if it isn’t plugged into the rest of the novel the way it should be. I read and re-read it because there is always something to notice. I don’t know at what point one of his books can be exhausted (I think I’m at 10 readings), but with judicious intervals, these planet stories not only entertain, but provoke thought and reward the attention you give them.
What else they do, as most people know, is help you understand his non-fiction writings by embodying ideas in characters who not only explain their views in dialogue, but play them out in imagined situations. In this book, mainly, and in the whole series as well, the ideas in The Abolition of Man.