The BAU team begin to track a family in Alabama who are working together to abduct young women. The family travel from city to city leaving clues behind, but their route becomes increasingly difficult to follow.

Dr Ephraim Goodweather and his team investigate a plane that lands in New York City with everyone on board dead. Pawnbroker Abraham Setrakian is convinced that something sinister is beginning.

After a tiger mauls a woman to death, Stabler heads undercover to gain access to an animal smuggling ring while Benson poses as a sex worker.

After a double homicide in the Everglades, the team go up against the Russian mob that's based in Miami.

Michael helps a Russian woman whose sister was smuggled into America by gangsters and is being held captive.

Locke, Sayid and Kate investigate a strange structure and its mysterious inhabitant; Sawyer competes in a ping-pong competition to get back his belongings.

The team looks into the death of a wealthy racehorse owner after he dies during a race. Meanwhile, Horatio learns that Ryan has a connection to the case.

Delirious Eko wrestles with past demons; some of the castaways go to the Pearl station to find a computer they can use to locate Jack, Kate and Sawyer; Jack does not know whom to trust when two of the Others are at odds.

Charlie exhibits peculiar behaviour when Claire has an idea that could get everyone rescued; tensions mount between Sayid and Locke as they continue their journey to rescue Jack.

Jack's fellow survivors realise that an Other is accompanying him; a mysterious illness strikes Claire.

Despite Calleigh's protests, Delko gets involved with his dangerous father. Meanwhile, Horatio tries to save Yelina.

Jack and the castaways begin efforts to make contact with Naomi's rescue ship.

After learning that the Others' pregnant women all died before giving birth on the island, Sun allows Juliet to examine her; Desmond allows an unlikely nemesis to help save the life of a new, mysterious island inhabitant.

The team travel to Mexico to protect a government minister whose efforts to combat the drug trade have made him a target.

Ben begrudgingly introduces Locke to the island's secrets, including mysterious Jacob; Juliet's secret goes public.

Jack and the castaways begin efforts to make contact with Naomi's rescue ship.

A home invasion turns into something more when the team discovers that the Russian mob is targeting the group.

Sun and Jin continue to search for each other; Locke confronts his enemy.

Jack, Sydney and Nadia learn that Irina Derevko (Lena Olin) is alive, and they head out to find her to thwart Elena Derevko's (Sonia Braga) Rambaldi scheme.

An agent's life hangs in the balance as the team races to track down Nadia's childhood caregiver, Sophia (Sonia Braga); Sydney and Nadia question Sloane's trustworthiness now that his obsession with Rambaldi has been renewed.