Ninety-seven years after the planet Earth was destroyed, generations of survivors are faced with dwindling resources.
A mission to locate Jasper is arranged once it's revealed he is alive; in hope of getting to Earth, Abby turns to Raven for help.
Clarke, Wells and Finn search for a seaweed antibiotic to help Jasper; a loveable 13-year-old named Charlotte joins Bellamy and his crew as they search for food.
Clarke and Finn grow closer after a shocking death; Abby tries to give Raven a chance to hide in the escape pod headed for Earth.
Clarke and Finn's new romance is threatened; after suffering a blow to the head, Octavia wakes up under the watch of a grounder; Kane plan is exposed.
Bellamy leads the search for Octavia into Grounder territory; Raven notices the connection between Finn and Clarke.
Abby helps Clarke with a dangerous procedure in hope of saving one of their own; Kane starts to feel guilty about his decisions.
Bellamy and Clarke search for supplies for winter; Octavia helps a friend escape; treacherous actions are revealed.
Finn and Clarke's attempt at brokering peace doesn't go as planned; Lincoln and Octavia become closer; a tragedy occurs during a celebration.
Murphy claims to have been captured and tortured by the Grounders; after sneaking away to find Lincoln, Octavia returns with a serious warning; the camp is struck by a mysterious virus.
During a hunt for food, Finn and Clarke end up in a compromising position; Bellamy receives an irresistible offer from Raven; Kane takes a risk.
Finn and Clarke encounter a new enemy; Bellamy tries to save Jasper; Murphy finally gets revenge.