The movie description is wrong.
In some ways, the film is based on the terrorist occupation of a theater that took place in Russia in 2002. The terrorist attack at the Dubrovka Theater Center on Melnikov Street (near Dubrovka Metro Station), Moscow, Russia was a hostage crisis of 23 until October 26, 2002.
Terrorists take 916 spectators hostage, demanding the withdrawal of Russian troops from Chechnya and an immediate end to the Second Chechen War. After 2 and a half days of siege, the Russian special forces OSNAZ conduct an operation to neutralize the terrorists, introducing a secret gas chemical agent into the ventilation system of the theater. As a result of the operation to release the hostages, all the terrorists were eliminated. 129 hostages died during the operation.
The film follows a similar terrorist act, but is filled with Hollywood-style excess action, as well as verbosity in some dialogues.
It's worth watching to see the continuation of the first series itself. Unfortunately, the second series is much less intelligently presented.
7/10 is a fair rating.