After a 40-year armistice in the war between the Twelve Colonies and the Cylons, the latter group launches a surprise attack with a goal of exterminating the human race, wiping out virtually everyone in the Twelve Colonies. Malware placed in the Colonial military's computer network renders most of the network ineffective or destroyed -- except for Battlestar Galactica, a space battleship that fought in the earlier war. Because it's older computer systems are not networked, the ship is not affected by the malware attack and it becomes the lead in the new battle with the Cylons.
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.
Former scientist Sam Beckett finds himself trapped in time due to an experiment gone awry, leaping into the body of a different person each week. Al Calavicci, at first known only as The Observer, is Sam's holographic adviser -- he provides Sam with some details about his new identity and gives him guidance on how to help the people affected by his presence. But with little memory to help guide him, our hero is forced to bluff his way through many a wacky situation.
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."