He's not exactly a prisoner, yet. He's kind of wedged and stuck in the entrance.
While Alexei, contemplates how to get him unstuck, the shockwave bounces back, but feels significantly stronger. Significantly so. Str+size check of 9+ is required to remain standing.
((Everyone in this story should go ahead and roll the same Str+Size check to remain standing. Those who fail will feel themselves literally picked up and placed onto the ground in an extremely precise and orderly manner.))
Just before the shockwave comes back"Fiona, hold fast! The shockwave is coming back!" Fiona feels something brush up against her foot, and glancing down she sees that Apollodorus' body is now next to her. "It should center on my body. It is my hope that you're being on both the mundane side and this side of the regio at one time that you'll prove to be an anchor keeping the connection to the mundane world open. Tell Maris that the book is not for House Tremere. Efforts to retrieve it will result in its destruction. Be wary of those of House Guernicus, not all are what they appear to be. It is possible that Laetitia is being held by her superiors, against her will. Goodbye, Fiona. Extend my farewell to my sodales. There are some instructions in my sanctum."