Elena comes home to a nightmare; Damon realises Katherine has returned; Tyler receives a surprise visit from his uncle.

Elena, Damon and Alaric go to Duke University to find Isobel's research into the paranormal and look for clues to the mystery surrounding the Lockwood family; Stefan faces a new danger in the woods; Tyler makes a shocking discovery about Mason.

Tyler demands Mason tell him the truth about their family, and Stefan tries to find out the reason why Katherine returned to Mystic Falls.

Desperate and confused, Caroline leaves the hospital. Damon is suspicious of Tyler's uncle. Bonnie unleashes her anger on Damon.

Following the subway tunnel collapse, Ruzek and Kidd treat injured passengers and track down the missing offender; Archer and Frost perform a life-saving amputation; Lenox feels the weight of the CPD's hopes as she fights to save one of their own.

Jeremy offers to help Alaric and Damon deal with Katherine; Caroline and her mother share some quality time together; Bonnie accidentally finds new information about Mason.

Tyler learns more about the Lockwood family curse; Stefan and Damon argue over how to handle Mason; Mason gives Sheriff Lockwood startling information.

Elena tries to entice Rose; Jeremy's actions force Stefan to put himself in danger; Caroline makes a terrifying discovery.

Caroline helps Tyler prepare for his first transformation; Alaric and Damon are suspicious when a stranger arrives in town; Luca and Bonnie work on a spell.

Spirits of the dead invade Mystic Falls during preparations for a traditional celebration; Damon has an especially violent encounter with an angry spirit; Alaric finds a long-hidden clue.

Elena and her friends start their senior year with their heads still spinning from recent events; Damon is unhappy with his new houseguest; Matt goes to Bonnie for help; Stefan works on his most-recent task.

Brennan and Booth investigate the college basketball world to determine who is responsible for the murder of a player on a nationally ranked team.

A baseball coach is found dead in the locker room, and a star player is also killed. Jane and Maura are called in to investigate.

Frank tries to get closer to Dottie while Fiona meets a now married high-school crush of hers and Kev thinks about buying the Alibi.

Fiona deals with the consequences of sleeping with Craig when his angry wife shows up at the door. Debbie develops a stress-rash and Fiona wonders if she's putting too much responsibility on the kids.

Dr Connor Rhodes must deal with his past when he takes care of a family friend; Dr Halstead struggles with a surgery that could impact a young musician's hearing.

Rhodes and Zanetti race to save a member of Firehouse 51, April's brother struggles during his first day at the hospital, and a woman saved from a burning building leads to a bigger mystery.

Castle and Beckett find themselves on a Grimm hunt to catch a fairytale killer before he kills again. However, nothing is as it seems in a case filled with deceit, betrayal, secrets and murder.

Voight and the team take a look at a house that has been linked to a series of gangs; Halstead struggles to maintain his composure when he is confronted by people from his past.

Dr Manning's actions with a recent patient lead to serious repercussions; April and Noah disagree over a patient who is injured after a beating; Dr Charles is visited by a childhood friend with a surprising revelation.