When a mysterious alien organism takes Dr. Keller as its host, Beckett and the crew must search for a serum to save her from the intruder.

Atlantis races to save team members who are trapped in a collapsed compound; a pregnant Teyla begs Kanann to help save her.

Following another unsuccessful search for Teyla, Sheppard returns home to Atlantis to find the city completely abandoned.

An old friend's return spurs a race against time to rescue a missing teammate.

Teyla continues to search for her people; a mysterious illness sweeps through the galaxy.

Col. Carter asks Teal'c to serve as Ronan Dex's mentor before his suitability review by the IOA.

Carter, McKay and Dr. Keller become trapped in an underground mining chamber during an off-world mission.

After learning of his father's death, Sheppard becomes embroiled in a covert experiment when he returns to Earth.

Sheppard and McKay agree to accompany a young princess on a rite of passage in order to maintain diplomatic relations.

Members of the Atlantis team are trapped in various sections of the city after an alarm initiates a quarantine lockdown.

The Atlantis team salvages a partially damaged Hive ship and retrieves information that may help in its war against the Wraith.

After being armed with the means to track Replicator ships throughout the Pegasus Galaxy, the Atlantis team works toward eliminating the Replicators.

When a mysterious drone crashes into the city, the Atlantis team's worst fears may be realized.

When McKay's sister is kidnapped, the team returns to Earth to find her.

While searching for her people, Teyla and the team meet a man who predicts a frightening future for Atlantis.

Teyla and Dr. Keller arrive on New Athos and discover that the entire settlement has been abandoned.

After a virus infects nearly everyone in Atlantis, McKay discovers cryptic letters and has no recollection of his identity.

Lt. Col. Sheppard is taken prisoner aboard a rogue ship run by a ruthless human commander.

While on an exploratory walk on a jungle planet, Lt. Col. Sheppard touches a crystalline growth and becomes host to an infectious energy form.

Ronon reconnects with a group of Satedans from his past that enlists the help of the Atlantis team on a mission against the Wraith.

Lt. Col. Sheppard leads his team on a high-risk mission to the core of the Replicator home world; Samantha Carter races against time to locate the city of Atlantis.

A team of explorers made up of soldiers and scientists travels through a Stargate, an ancient portal to other planets. They use the Stargate to explore new worlds, forge ties with friendly civilizations and protect Earth from hostile forces. The TV series is based on the theatrical film "Stargate."

Led by the brilliant scientist Dr. Nicholas Rush, a band of civilians and soldiers faces a whole new world -- and fights for survival -- after their secret military base is attacked. The survivors emerge aboard an ancient ship, unable to return to Earth and now on a course to parts unknown. Amid the darkness the group must meet its most basic needs of food, water and air while discovering the secrets of the ship's Stargate to ultimately survive.

Set in deep space, the series revolves around the adventures of Dylan Hunt, captain of the Andromeda Ascendant, his crew members, and their efforts to restore the Systems Commonwealth, a government that was responsible for a time of extended peace and prosperity. The sci-fi series is based on previously unused materials written by late writer Gene Roddenberry.

This update of the late-1970s series takes a decidedly darker tone as what's left of humankind struggles for survival against the robot Cylons, who have killed millions. The Galactica, led by William Adama, protects a patched-together fleet of civilians -- led by de facto president Laura Roslin -- in search of a mythical planet called Earth.

In the tradition of the 1960s cult show of the same name, this anthology series features different actors, many well-known from their previous work, in each episode. The episodes often explore eerie and often supernatural themes with a science-fiction element.

A spinoff of "Star Trek: The Next Generation," "Deep Space Nine" is set on a space station near the planet Bajor. This time, Commander Benjamin Sisko is in charge of a diverse crew. But unlike other "Star Trek" series, there's no USS Enterprise to help them. Sisko and the crew must fight off rival alien species who want control of Deep Space Nine because of its strategic position close to a wormhole, which allows speedy travel to the far reaches of space.

Kathryn Janeway is the captain of a starship that is lost in space and must travel across an unexplored region of the galaxy to find its way back home. On its way, the crew encounters different species they must deal with, but find that all their adventures only make them long for home.

Featuring a bigger and better USS Enterprise, this series is set 78 years after the original series -- in the 24th century. Instead of Capt. James Kirk, a less volatile and more mature Capt. Jean-Luc Picard heads the crew of various humans and alien creatures in their adventures in space -- the final frontier.

Quinn Mallory has a problem: He's discovered a way to travel to other dimensions. So what's the issue? Like Sam in "Quantum Leap," he can't get back home. But don't worry; he's not lost alone.