The CW's Arrow Returns for its Eighth and Final Season

The hub of The CW superhero world returns for a final season, as spin-offs from two wildly successful film franchises debut new episodes, the MLB Playoffs continue, and twelve presidential candidates square off in the latest Democratic debate. Here are the highlights.

SEASON PREMIERE: The CW is promising to pull out all the stops for Arrow's eighth and final season, with big plans for this year's crossover episodes, and perhaps even more Arrowverse shows after the mothership bids adieu. In tonight's season premiere, Oliver (Stephen Amell) crosses paths with some familiar faces and William (Ben Lewis) and Mia (Katherine McNamara) combiine forces to battle a new enemy. Watch the preview. 9:00 PM ET on The CW

SERIES PREMIERE: Expanding the world of Robert Ludlum's Bourne series, Treadstone explores the origins of the project that gave the world Jason Bourne. Watch the preview. 10:00 PM ET USA

SEASON PREMIERE: Also expanding the world of a popular film series is The Purge, which returns tonight for its second season, with characters facing the fallout from twelve hours of completely unchecked crime. 9:00 PM ET on USA

SPORTS: Game Four of the MLB Playoffs sees the Saint Louis Cardinals playing the Washington Nationals at National Park in Washington. 8:00 PM ET on TBS

DEMOCRATIC DEBATE: CNN and The New York Times are co-hosting tonight's Democratic Debate from Otterbein University in Westerville, Ohio. A record twelve candidates will square off, with Erin Burnett and Anderson Cooper moderating. 8:00 PM ET on CNN

ALSO TONIGHT

• Emergence finds Jo (Allison Tolman) trying to keep Piper (Alexa Swinton) safe after learning more about the child's background. 10:00 PM ET on ABC
• This is Us sees Rebecca (Mandy Moore) visit Randall at college, while Kate (Chrissy Metz) and Toby (Chris Sullivan) spend some quality time with baby Jack. 9:00 PM ET on NBC
• New Amsterdam finds Iggy (Tyler Labine) and Kapoor (Anupam Kher) battling city bureaucracy, while an attempt to help a patient goes awry. 10:00 PM ET on NBC
• Mixed-ish joins Rainbow (Arica Himmel) as she explores her complex family history. 9:00 PM ET on ABC

Mike Attebery is Senior Editor at Primetimer and the author of seven mystery thrillers. Follow him on Twitter at @mikeattebery.