Picking up on the same night as last season's finale, Elena (Nina Dobrev) arrives home to a nightmare as she discovers Uncle John's and Jeremy's fate. At the hospital, Sheriff Forbes (guest star Marguerite MacIntyre) is comforted by Matt (Zach Roering), Bonnie (Katerina Graham) and Damon (Ian Somerhalder) while she waits to hear if Caroline (Candice Accola) will survive the car accident. After a confusing conversation with Elena about the night's events, Damon is the first to realize that Katherine (also played by Nina Dobrev) has returned. Katherine's arrival sends Stefan (Paul Wesley) and Damon on a path to find out what she wants, why she's back, and how much of a threat she is to the people they love. Meanwhile, still reeling from his father's death, Tyler (Michael Trevino) is surprised when his charming and mysterious uncle, Mason Lockwood (guest star Taylor Kinney, "Trauma"), arrives to console the family.