Battlestar Galactica is set in a distant star system, in an age described as "the seventh millennium of time." Twelve colonies of humans, living on different worlds, have been fighting a 1,000 year war against the robotic race of Cylons, who seek to exterminate all of humanity. The Cylons have unexpectedly sued for peace, through the diplomatic agency of a human, Count Baltar. The human leaders, called the Council of the Twelve (with one representative from each colony), and the commanders of their military fleet are all too pleased by the Cylon offer of peace, which ends so many years of warfare. The powerful "Battlestars" are assembled for armistice talks with Humanity's age-old robotic enemy. But it's all a deception – Baltar has betrayed humanity for personal gain, and the Cylons have no intention of making peace.
Only Commander Adama, of the battlestar Galactica, suspects that the Cylons are planning a trap, and orders a recon patrol, consisting of his two best pilots: his eldest son, Apollo, and Lt. Starbuck. Adama's younger son, Zac, convinces Starbuck to let him go in his place. The patrol discovers a vast Cylon armada waiting in ambush behind a moon named Cimtar, but the Cylons jam their communications. Cylon fighters pursue the two Vipers, and Zac's fighter is hit. This forces Apollo to leave him behind, so that the fleet can be warned. Zac's Viper is destroyed by the Cylons just before he reaches the fleet.
Baltar manipulates President Adar into prohibiting the launch of fighters as the Cylons close in on the fleet. Frustrated, Adama orders the Galactica's Viper squadrons be placed on full alert, with their fighters ready to launch. As the Cylons attack, the Galactica is able to launch its fighters first, while the other battlestars are caught off-guard. The Atlantia, with President Adar aboard, is destroyed, as are apparently the other battlestars; Galactica alone survives the Cylon assault. Apollo informs Adama that the Cylons were accompanied by refueling tankers, and Adama realizes that this would allow the fighters to operate far from their base ships (known as "basestars"), which must be operating somewhere else. He orders the Galactica to withdraw and protect the planet Caprica, Adama's homeworld, but they are too late, as the Cylon fleet has launched simultaneous massive assaults on all the Colonies at the very same time the attack on the battlestars has commenced.
With the Colonies in ruins, Adama collects as many survivors as possible, and orders every intact civilian ship to take survivors and follow the Galactica. They hope that the Galactica can protect this ragtag fleet long enough to find the legendary thirteenth human colony. It is called Earth, but the location of this lost colony is known only to the last lord of Kobol, the planet which was the original home of Man, but which was abandoned thousands of years earlier, when the Thirteen Tribes migrated to the stars. Helping Adama in the quest for Earth are his son, Captain Apollo, commander of the Galactica's strike wing; Lieutenant Starbuck, the Galactica's best fighter pilot and Apollo's best friend; Lieutenant Boomer; and Colonel Tigh, Adama's second-in-command.
The Cylon Imperious Leader, determined that no human at all shall survive, orders Baltar's execution after his usefulness is over, but (as retro-actively revealed in the TV series version of the film) he is spared at the last moment in order to help the Cylons hunt down the human fleet. After initially escaping the Cylons across a massive starfield called the Nova of Madagon (referred to as such due to its extremely dangerous, hot environment, and Cylon mines), the Galactica and the fugitive fleet find brief respite on the resort planet of Carillon, where they hope to find food and fuel for their journey. As much of the fleet's food supplies were contaminated by pluton bombs during the Cylon attack, the fleet is in desperate straits, and must find a food source soon or face starvation.
It quickly becomes apparent that there is more to Carillon than meets the eye. The fact that Carillon has more than enough food and fuel for the fleet's needs makes Adama wary. It is also apparently the largest tylium (fighter fuel) mining facility in that part of the galaxy, as well as a popular gamblers' den, but nobody has ever heard of the place. Adama discovers that Baltar was responsible for performing the initial Carillon survey, and reported that tylium was too minimal for mining, and he immediately smells a Cylon trap.
But in the meantime, Sire Uri, Adama's self-serving nemesis on the new Council of the Twelve, uses the opportunity the planet presents for the morale of the fugitives to make his move against Adama, whose strict but selflessly benign intentions hinder his own ambitions. The Council of the Twelve, led by Uri to believe the Cylons have been left far behind, propose that the humans pause to celebrate their escape and dismantle their military and weapons to prove to the Cylons that humans are no longer a threat to them. The Council arranges a banquet on Carillon, and orders all fighter pilots to attend. Adama suspects that this might be a golden opportunity for the Cylons to launch an attack on their fleet, and orders Colonel Tigh to surreptitiously hold back their fighter pilots from attending the party while he is to outfit noncombat personnel with fighter uniforms.
Down on Carillon, Apollo and Starbuck gradually discover that something is amiss when they see strangers walking around clad in the uniforms of their squadron, and after some investigation they discover the truth behind the planet's prosperity. The natives of Carillon, the insectoid Ovions, have set up the gambling resort to lure humans to them to serve as living food for their hatching larvae in their underground chambers. They are also secretly in league with the Cylons and mine the tylium solely for their purposes in exchange for their freedom, and they are cooperating in the Cylons' efforts to eradicate the human fugitives. During a subsequent fight with Cylon soldiers, the laser fire from both parties sets the tylium mines on fire, threatening to destroy the planet once the fire rages fully out of control.
Adama's ruse works, and the Cylons, believing that all of the pilots are at the banquet, launch a fighter attack against the Galactica in orbit, but Adama is ready to spring his trap. Once the Cylon fighter contingent is fully engaged with the Galactica, Adama recalls all his Vipers from the surface of Carillon, taking the enemy by surprise. During the fight, Apollo realizes the Cylon fighters couldn't have come so far without a basestar, and he and Starbuck disengage from the battle and find a Cylon basestar hidden on the far side of Carillon. In defiance of Commander Adama's recall order, they decide to attempt to destroy it, in order to enable the refugee fleet to elude pursuit, and use fake radio chatter to fool the basestar into thinking it's under attack by multiple Viper squadrons. The basestar descends into Carillon's atmosphere to avoid detection, and is destroyed when the planet finally erupts in a massive tylium explosion. Despite their victory, however, the humans realize their enemies will still be pursuing them, and they set out to Earth, their last hope for survival.
There have been various versions of the pilot broadcast or released theatrically. Although produced for television, originally as part of a planned series of telemovies and eventually as a television series, Universal Studios decided to release a reedited version theatrically in order to recoup some of the high production costs with producers believing the series "could be a fine shot at a corner of the Star Wars market." In July 1978, two months before its U.S. television debut, the film was released in Canada, Australia, and some countries in Europe and Latin America. The release was a success following an aggressive marketing campaign from Universal and influenced the decision to release the Buck Rogers in the 25th Century pilot in cinemas a year later. Later episodes of the regular Battlestar Galactica series were also re-edited and released in cinemas internationally.
Although there are many minor differences between the broadcast pilot and the cinema release, the most notable is the fact that, in the film version, Baltar is executed by the Cylons, whereas, in the television version, he is held for public execution before later being shown mercy by the Cylons, and going on to be a major character in the TV series. The cinema release also made use of Universal's Sensurround process, and was the last produced film to use it.
The television version was first broadcast in the U.S. on September 17, 1978. This original three-hour broadcast was interrupted for more than an hour to televise the signing of the Camp David Peace Accords between Israel's Menachem Begin and Egypt's Anwar Sadat, overseen by President Jimmy Carter. Following the coverage, ABC resumed the broadcast, right where it was interrupted. In later years, this version has often been split into three episodes, each an hour long, for syndication.
In May 1979, following the broadcast of the final episode of the regular series, the overseas theatrical version saw a limited release at select US screens.
In 1980, the pilot was edited again and syndicated as part of a series of re-edited Battlestar Galactica telemovies.
Both the theatrical version and the television version have been released on DVD. The television version was released on the season 1 DVD set, and as part of "The Complete Epic Series" boxset containing all episodes of the series. The theatrical version was released in 1999 and then again in 2003 as a "flipper" disc with a preview for the then-current Battlestar Galactica revival and a Cylon DVD game. These releases present the theatrical version in 1.85:1 "matted" (non-anamorphic) widescreen with the "Sensurround" track in Dolby Digital 1.1 Mono.
In 2013, Koch Media released this version in a 3 film DVD set with "Mission Galactica: The Cylon Attack", and "Conquest of the Earth". This DVD release uses HD masters supplied by Universal and all films are presented in 1.37:1 full frame as they were shot in, as opposed to the "matted" widescreen 1.85:1 ratio seen theatrically.
Koch Media released the entire series in Germany on a Blu-ray set in January 2014. This set contains all the episodes of the series (including Galactica 1980), utilizing the masters Universal used for their DVD releases, in 1080p with English 5.1 Surround and German mono. This set only contains the full-length TV versions of Saga of a Star World and the other episodes used to make the films Mission Galactica: The Cylon Attack (from The Living Legend and Fire in Space), and Conquest of the Earth (from Galactica Discovers Earth and The Night the Cylons Landed). The Koch set does however, contain the original theatrical trailers for all three films including the Super 8mm versions, along with other extras and fan convention material exclusive to that release. In May 2015, Universal released the complete series on Blu-ray in enhanced widescreen and 4:3 versions. The Universal Blu-ray sets carry over most of the extras from the previous "Complete Epic Series" DVD set with a few new ones included.
In February 2013, Universal Home Entertainment released the theatrical version for the first time on Blu-ray in North America with a new, remastered HD transfer in widescreen 1080p, the "Sensurround" track in DTS-MA 1.1 Mono, and a preview for Battlestar Galactica: Blood & Chrome. In October 2015, Koch Media released their own Blu-ray of the theatrical version using Universal's HD transfer in widescreen and unmatted 4:3 full frame formats. Extras include the German trailer and vintage German opening credits from a 16mm print.A photonovel of the film was released in 1979, and is considered a highly prized collector's item. While much of this demand was due to each image on each page being taken directly from the actual 35mm film cells, compounding the value was the scarcity of intact copies; the glossy paper used for the print stock did not adhere well to the spine glue, and after several reads the binding tended to fall apart. This was further compounded as the glue became brittle with age.
Stu Phillips' soundtrack to the pilot, as performed by the Los Angeles Philharmonic has been released on various occasions in the past, including a re-recorded LP, released in 1978 by MCA Records around the time of the film's TV debut. This was followed by a dedicated CD in the boxset entitled The Stu Phillips Anthology – Battlestar Galactica containing the original film tracks for the first time. In 1999, it was also re-recorded by the Royal Scottish National Orchestra, conducted by Phillips himself, and issued on CD. It was issued again in February, 2011, by Intrada Records featuring the complete score as recorded for the film by the Los Angeles Philharmonic.
A paperback novelization of the film was published in 1978.
The story was adapted into comic book form by Marvel Comics, first in a magazine format, then later in both tabloid format and as a trade paperback.
An audio drama version was created by editing the film's mono sound and adding narration voiced by Lorne Greene and released on MCA Records in 1979 under the title "The Saga of Battlestar Galactica", Catalog #3078. The vinyl version features a gatefold sleeve with liner notes. It runs approx. 50 minutes.
The plot of Part I formed the primary plot of the reimagined Battlestar Galactica miniseries, in which the Twelve Colonies are destroyed, and the survivors set out for Earth.
The reimagined series episode "The Passage" is loosely based on the plot of Part II, in which the fleet must navigate through a radiation belt.
Director Bryan Singer stated that the planned Battlestar Galactica feature film would be based on this part of the 1978 television series, but would not be a direct adaptation. However, Singer is no longer attached to the project, and subsequent scripts may no longer reflect this.