What to Watch on Friday: ‘Z Nation’ starts second season

Z Nation (10 p.m., Syfy) – In the Season 2 premiere, everyone tries to escape the impending nuclear blast. Also, Citizen Z battles thawed zombies and issues an air bounty for Murphy.

Also on tonight . . .

Cold Justice (8 p.m., TNT) – The team travels to White Settlement, Texas, to investigate two different murder cases at the same time. The episode will be continued next week.

Redwood Kings (8 p.m., Animal Planet) – In the two-hour season finale, the crew, inspired by the work of Leonardo da Vinci, builds a gigantic medieval workshop for the biggest amusement trade show in the world, making this their most ambitious build ever.

Think It Up (8 p.m.) – In this special, airing on CBS, ABC, NBC and Fox, celebrities spotlight stories of teachers and students working together on projects.

9/11: The Miracle of Stairway B (8 p.m., History) – The History Channel airs several 9/11 specials today, including this special about 16 trapped survivors.

This story was originally published September 11, 2015 at 2:00 AM with the headline "What to Watch on Friday: ‘Z Nation’ starts second season."