What to Watch on Tuesday: ‘The Flash’ and ‘DC’s Legends’ return on The CW

The Flash (8 p.m., The CW) – With Barry in the speed force in the Season 4 premiere, Iris, Kid Flash, Joe and Vibe must protect Central City.

This Is Us (9 p.m., NBC) – Randall and Beth get exciting news, while Rebecca tries to reconnect with Jack.

DC’s Legends of Tomorrow (9 p.m., The CW) – In the Season 3 opener, the Legends realize they broke the timeline, so Rip Hunter arrives to relieve them of duty.

The Mayor (9:30 p.m., ABC) – Courtney discovers that his old elementary school’s music program is in danger of being eliminated.

Kevin (Probably) Saves the World (10 p.m., ABC) – Yvette attempts to guide Kevin in his mission to help others, but his good intentions go awry.