A possible concise summary is:
The text is a fictional account of a janitor who became a containment specialist for SCP-173, a concrete statue that kills people when they blink. He was locked in a cell with three prisoners and the statue as part of an experiment. He survived by realizing that the statue did not want to kill him, but to communicate with him. He saw visions of other statues hiding in the world and became mentally affected by the experience. He was injected with a drug and became like the statue himself, trying to strangle anyone who approached him. He was related to Dr. Siegfried Schwarz, who approved the experiment.
Here are some key facts extracted from the text:
1. The narrator was a containment specialist for SCP-173, a dangerous and fast-moving anomaly that snaps the necks of anyone who breaks eye contact with it.
2. The narrator and his team were locked in SCP-173's cell as part of an experiment to test their endurance and reaction to the anomaly.
3. The narrator was the only survivor of the experiment, but he was mentally affected by SCP-173 and started to exhibit its traits and behaviors.
4. The narrator's uncle Siegfried was involved in the experiment and approved the report that declared the narrator incurable and incarcerated.