What to Watch on Sunday: Showtime docu-series ‘Action’ goes inside sports gambling

NCAA Tournament (CBS, TBS, TNT, truTV) - The Second Round of the 2019 NCAA basketball tournament continues today, with games spread over four networks. Round 2 continues tomorrow. We have your complete viewing guide here, with the schedule, channels and streaming options.

Action (8 p.m., Showtime) - This new four-part documentary series directed by Luke Korem looks at the legalization of sports gambling, a $400-$500 billion dollar industry. The series chronicles the lives of professional gamblers, bookies and oddsmakers throughout the 2018 NFL season, culminating with Super Bowl Sunday.

Prince Charles at 70 (8 p.m. PBS / UNC-TV) - A look at the life of Prince Charles as he celebrates his 70th birthday with Prince William, Prince Henry and his wife Camilla.

American Idol (8 p.m., ABC) - Lots of hopeful singers will get sent home in tonight’s Hollywood Week episode (Hollywood Week continues on tomorrow’s episode).

Shark Tank (10 p.m., ABC) - We get an update on the Chapel Hill business owner — remember The Cut Buddy? — who got a Shark Tank deal in 2017.

Some programming descriptions are provided by networks.