Quick recap
Sara Lance is killed by three arrows early on, and the hunt for her killer leads Oliver to Ra's al Ghul, the immortal head of the League of Assassins. Laurel trains to become the Black Canary and Thea becomes Speedy. Oliver challenges Ra's to a duel, is run through and thrown off a cliff, but survives. The truth comes out: Thea killed Sara while drugged by Malcolm. To save his sister, Oliver agrees to become Ra's's heir, Al Sah-him. It's a plan to topple the League from within: he stops a virus from being released on Starling City and kills Ra's. Malcolm takes over as Ra's. Oliver hangs up the hood and leaves with Felicity.
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