The novel “Zona II: Sabertooth Uprising” by Fred G. Baker was published for the first time in 2023. It’s the second book in the Zona series and follows “Zona: The Forbidden Land”.
Grant Taylor and his group of explorers camp in the core of the crater called Zona with the idea of spending the winter there. They formed an alliance with the giant dire wolves that live in the Zona but discover that the sabertooth lions have warlike intentions.
Max Volkov managed to return to St. Petersburg, where he joins Boris Ustinov to set up a new expedition to Zona that brings supplies to the group that stayed there there. This takes time, also because it’s necessary to maintain the secret of the location of the crater and what Max and his traveling companions found there.