A race of giant Gastropods has taken over the planet Jaconda. Their leader, Mestor, now intends to cause an enormous explosion in order to spread his people's eggs throughout the galaxy, and he kidnaps juvenile twin geniuses from Earth to work out the necessary mathematical equations. Space fighters led by Lieutenant Hugo Lang are dispatched to get the twins back, but they come under attack and Lang is the sole survivor when his ship crashes on the asteroid Titan III. A newly regenerated Doctor and Peri become involved and help Jaconda's elderly former ruler Professor Edgeworth, who is really a Time Lord named Azmael, to defeat Mestor and free the planet's bird-like indigenous people from the gastropods' reign of terror. Azmael, however, sacrifices his life in the process.

June and Jennifer Gibbons are twins from the only Black family in a small town in Wales in the 1970s and '80s. Feeling isolated from the community, the pair turn inward and reject communication with everyone but each other, retreating into their own fantasy world of inspiration and adolescent desires. After a spree of vandalism, the girls are sentenced to Broadmoor, an infamous psychiatric hospital, where they face the choice to separate and survive or die together.

Widowed Welsh mother Anna Leonowens becomes a governess and English tutor to the wives and many children of the stubborn King Mongkut of Siam. Anna and the King have a clash of personalities as she works to teach the royal family about the English language, customs and etiquette, and rushes to prepare a party for a group of European diplomats who must change their opinions about the King.

Two identical twin sisters, separated at birth by their parents' divorce, are reunited years later at a summer camp, where they scheme to bring their parents back together. The girls, one of whom has been living with their mother and the other with their father, switch places after camp and go to work on their plan, the first objective being to scare off a gold-digger pursuing their father.

Olivia and Matthew Grey, 18-year-old twins born into a world of privilege and high expectations. There are almost no boundaries between them - even their dreams are connected.

Caio is a deeply religious young man, living in the shadow of his brother, Alberto. While Alberto challenges norms and embraces life, Caio feels trapped by his beliefs. In a moment of desperation, Caio murders Alberto and stages his death as a suicide, convincing himself that he acted in God’s name.

Ned Kendall is asked to return to the remote and isolated family home by his sister, to say goodbye to his father who is dying. Ned also brings his young aspiring actress fiancee who struggles with the isolation. When home he starts having memories of his childhood many involving his beautiful twin sister and his older brother. These memories awaken long-buried secrets from the family's past.

Jean Claude Van Damme plays a dual role as Alex and Chad, twins separated at the death of their parents. Chad is raised by a family retainer in Paris, Alex becomes a petty crook in Hong Kong. Seeing a picture of Alex, Chad rejoins him and convinces him that his rival in Hong Kong is also the man who killed their parents. Alex is suspicious of Chad, especially when it comes to his girlfriend.

Twins Ronnie and Reggie Kray are raised in east London, under the influence of their hateful but doting mother Violet. As they grow up, Ronnie's violent nature takes over, and Reggie follows his brother's lead. The two become notorious crime lords who rule over the East End club scene. But at the height of their power, the brothers veer into different lives, giving the older crime bosses a chance to reclaim what the Krays took from them.

The working class twin sister of a callous wealthy woman impulsively murders her out of revenge and assumes the identity of the dead woman. But impersonating her dead twin is more complicated and risky than she anticipated.

Ruby and Garnet are identical twins, ten years old and inseparable. Since their mother's death they live with father and grandmother in the big city. When one day attractive Rose steps into father's life, Ruby and Garnet's whole life is turned upside down. They must leave their beloved granny and move to the countryside with father and that much hated "new one" because father wants to fulfill his most ardent dream to open a bookstore.

During the Great Depression, identical twins are separated at birth. One, Drexel Hemsley becomes a wildly successful '50s rock star, while the other, Ryan Wade, struggles to balance his passion for music and pleasing his parents, who want him to become a preacher. Finally, Ryan rebels against his parents' wishes and launches his own music career -- performing the hits of Drexel Hemsley. Ryan later learns the truth about Drexel when their fates tragically collide.