In the season finale, “Lian Yu,” fight battle between Oliver (Stephen Amell) and Adrian Chase (Josh Segarra) culminates in a final epic battle. After recent events, Oliver decides to recruit a group of unlikely allies -- Slade (guest star Manu Bennett), Nyssa (guest star Katrina Law), Merlyn (John Barrowman) and Digger Harkness (guest star Nick. E. Tarabay) -- to defeat Chase. However, Chase has his own army -- Black Siren (guest star Katie Cassidy), Evelyn Sharp (guest star Madison McLaughlin) and Talia al Ghul (guest star Lexa Doig) -- and the forces collide in an explosive season ending episode of “Arrow”.
Based on the characters from DC, the series revolves around billionaire playboy Oliver Queen (Stephen Amell) after a violent shipwreck, was missing and presumed dead for five years before being discovered alive on a remote island in the North China Sea. Oliver returned home to Star City, bent on righting the wrongs of his family and fighting injustice. As the Green Arrow, he protects his city with the help of former soldier John Diggle (David Ramsey), computer science expert Felicity Smoak (Emily Bett Rickards), his vigilante-trained sister Thea Queen (Willa Holland), former police captain Quentin Lance (Paul Blackthorne) and brilliant inventor Curtis Holt (Echo Kellum).
Newly appointed Mayor Oliver Queen found himself challenged as he fights on two fronts for the future of Star City. With Diggle back in the military and Thea adamant about hanging up her hood as Speedy, Team Green Arrow is down to just Oliver and Felicity – but they’re no longer the only vigilantes in town. Green Arrow’s public defeat of Damien Darhk at the end of Season Four has inspired a new crop of masked heroes to step up and defend the city, though their painful inexperience makes them obstacles, rather than allies, in the field. The arrival of a deadly new adversary forces Oliver to confront questions about his own legacy, both as mayor and as the Green Arrow.