What happened in The Vampire Diaries episode 10?

Season 1 Episode 10: Jeremy decides to return to his hobby of sketching fantasy creatures that he had stopped upon the death of his parents. Meanwhile, the vampire Logan attacks and kills several people throughout the town. Matt and Caroline continue to hang out together. He tells Tyler that he likes hanging out with Caroline. Sheriff Forbes tells Damon of a new recent attack, and he discovers Logan doesn't know who turned him. Alaric helps with a small dispute among Jeremy, Tyler and Mayor Lockwood. Logan kidnaps Caroline after a dispute with the sheriff, but Stefan and Damon save her. Logan tells Damon he knows of another way to resurrect Katherine. Elsewhere, Elena tells Stefan that she loves him and he decides to stay in Mystic Falls. Stefan and Elena then sleep together. But when Stefan goes to get a drink for Elena, she discovers the photo of Katherine and leaves his house abruptly, leaving her vervain necklace behind with the photo. Alaric confronts Logan and tells him to leave Jenna alone. Logan tries to attack him, but gets staked and dies. Elena is involved in a car crash while trying to avoid a man in the middle of the road, but realizes that the man is more than human. The last shot is of the stranger approaching the car and Elena screaming.

Season 2 Episode 10:

Stefan and Damon plot to get the moonstone from Katherine so they can lift the curse. Elena asks Rose to take her to Slater so they can learn more about Klaus and where to find him. Instead, they find Slater's staked corpse in his house. Elena uses information from his computer to get Klaus's attention, saying that she, the doppleganger, is willing to surrender. Rose protests, but Elena insists that surrendering is the only way to protect the people she loves from Klaus. Meanwhile, Caroline and Tyler discuss the approaching full moon and explore the underground tomb on the old Lockwood family property. They discover Mason's journal and the video diary that he had used to document his extremely painful transformations. Bonnie forms a plan to lift the spell from the tomb and temporarily incapacitate Katherine so that Stefan can quickly grab the moonstone, but Jeremy goes ahead with the plan by himself and is captured and fed on by Katherine. He manages to toss the moonstone out of the tomb. Stefan arrives and pushes Jeremy out safely, but is trapped in it himself. Later, Jeremy and Bonnie almost kiss. Damon arrives at Slater's house and tells Elena that he will not let her surrender to Klaus or put herself in danger. Elijah and two other vampires confront Damon, Rose, and Elena; the two unnamed vampires want to take Elena to Klaus, but Elijah kills them and leaves Damon, Rose, and Elena unharmed. Damon and Elena return to Mystic Falls; Elena tries to run to Stefan in the tomb, but Damon restrains her. Stefan makes Damon promise to protect Elena, and he agrees. Elijah and Luca's father discuss what had happened at Slater's house. Elijah states that he spared Damon and Rose because he could see that they would protect Elena, which is what Elijah had been trying to do all along.