10. East of Emma

Complete story — includes the ending

It's Emma and Sutton's 17th birthday and the Mercers promise Sutton a day full of festivities. Emma is aware that her time in Phoenix is coming to an end and she wants to come clean to the Mercers about her true identity before she leaves. She starts giving heartfelt goodbyes to Kristin, Ted, and Laurel, who have grown to be like family to her even though she hasn't been honest with them. Sutton arrives in Phoenix just in time for her birthday and her first order of business is to reel Emma in using Ethan as bait. Ethan declares his love for Emma to Sutton, who assumes her sister's identity at the computer. After speaking with Alec, Derek shows up at Char's house to win her back, but before she can respond, the police show up to take Derek into custody after receiving an anonymous tip about him. Char stands up to her mother at the police station when she wants to stay and vouch for Derek, but Alec insists that the two return home. Laurel wants Justin to be her date to Sutton's birthday party, but he is reluctant to face Ted after their last encounter. Emma returns to Sutton's room and finds an alert from Ethan telling her to meet him at the cabin, which was actually written by Sutton as a ploy. Sutton shows up to meet Ethan at the cabin and he assumes that she is Emma. The real Emma walks in just as Sutton and Ethan are making out. The twins have a bitter confrontation as Sutton accuses Emma of stealing her life (although it was Sutton who told Emma to take over her identity in the first place) and Emma defends herself, saying that all she really wanted in Phoenix was to build a relationship with her biological sister. Sutton then storms out and heads to her party to reveal Emma's lies. Emma and Ethan have a fall-out as Emma desperately wants to leave Phoenix before anything else happens and Ethan pushes her to fight for herself and not succumb to what Sutton wants. Emma calls Lexi to tell her how everything turned out and after their conversation, Emma decides to show up at Sutton's party after all. Emma and Ethan declare their love to each other and they wonder why Sutton had yet to arrive since she left the cabin long before they did. It turns out that while Sutton was driving to the party, a mysterious figure popped up from her back seat and shocked Sutton to the point that she had lost control of her vehicle and had driven into a lake. When it is time for Sutton's birthday speech, Emma is fully prepared to reveal herself to Sutton's family and friends, but as she is about to reveal her secret, she notices a strange figure behind one of the outdoor curtains and ends her speech before revealing anything. She heads out to find the mysterious person and Kristin follows her, identifying the person as "Annie." The last scene of the episode shows a panicked Sutton drowning with no one in sight.