I imagine this facility to be situated in a cold Slavic forest during a cool, crisp autumn. In fact, putting aside that I'm not particularly versed in Russian history, the tension between Lambridge's mildness and Petrushev's rashness has a Lenin-Stalin vibe to it. Also, I think the Garden Man is notably impersonal in his appearance in this story. I have my ideas on what kind of character he is, but I'd love to see him again in another story.
Also, Agent Paelfang - that's a surname people should run away from. Wonder if he'll return? Would you care to write about him, too? He's not especially characterized here but he could have potential.
I enjoyed the story very much. The digression with the researchers, Olga and Vaclav, delighted me lots.