Btw., the story needs to be read with a good critical sense. In the part already published, the version given by Chris Chivers differs strongly from the protocols of the Kulayev case. E.g., either the central witness, Mr. Misikov, lied in court, or Mr. Chivers "adapted" the story to the demands of a Hollywood script. I'd suppose the latter, to be frank.
Sadly and quite annoyingly, the warning is misleading.
The transcript of the first hearing of the Nurpashi Kulayev trial has a list of all those who were held hostage in Beslan: it's a huge list. Seven males on it bear the last name Misikov. That's potentially confusing, considering there are also five females named Misikova there and one Misikova-Karkuzashvili, who, in Chivers' text, is left with the second, Georgian, part of her last name - possibly, to avoid this namesake confusion - though, who knows.
Kazbek Misikov, the man whose story opens The School, is briefly mentioned in someone else's testimony during hearing #5.
Then, at hearing #16, there's a testimony of Yuri Misikov, a namesake.
And finally, at hearing #18, Kazbek Misikov testifies himself - and I can't say his testimony "differs strongly" - or at all - from what Chivers' wrote.