In the second of this two-part series, Liz Bonnin and the team return to the Russian Far East to track endangered Siberian tigers. The Siberian tiger is one of Earth's rarest and most elusive animals. As Liz Bonnin and cameraman Max Hug-Williams return to the snowy Russian forests they uncover a problem: only a few hundred 'snow tigers' remain in the wild and breeding females are in particularly short supply. Max is following a female tiger called Varvarra to see if she has new cubs, while Liz searches for a female called Princess who has gone missing. The team rescue an orphaned tiger cub, but have they found him in time? A remarkable and emotional journey into the hidden world of the Siberian tiger, revealing for the first time intimate footage of one of the planet's most powerful and mysterious big cats.

• Liz Bonnin