Invasion: Earthis a BBC science fiction TV series. It was made in collaboration with the Sci Fi Channel , and released in 1998 as six fifty minute episodes.
Episode 1: "The Last War"
England 1944, during the height of the V-2 rocket blitz on England, an unidentified and notably non-German object crashes, devastating the suburb in which it falls. A bomb disposalteam arrive on the scene, led by Lt. Charles Tyrell, an Oxford Don and anthropologist, but while searching the scene the soldiers discover two of the crashed craft's occupants; one is shot dead by a soldier while attempting to flee the scene (much to Tyrell's dismay), while the other occupant falls out of the craft, badly injured by the crash. It soon becomes apparent that the occupants are not human, with their domed heads and speckled pale skin. Tyrell establishes a rapport with the survivor, just as Military Intelligence arrives.
The action then moves to Scotland, 1998, and a joint RAF / NATO airforce base. Flight Lt. Chris Drake and his navigator, Jerry Llewellyn, are two Tornado aircrew scrambled to intercept an unidentified craft over the North Sea. During the ensuing encounter, both the base and the interceptors are seemingly attacked by a weapon that shuts off their power and disables all their instruments, so Drake impulsively acts against orders and shoots down the UFO. In the process, his own craft is damaged and he and Llewellyn must eject over the ocean. Drake is recovered alive but Llewellyn suffers serious injuries during ejection and dies in the sea before he can be rescued. The guilt-ridden Drake is grounded as a result of his hasty actions.
At the same time a local group of government-sponsored university students, who moonlight as amateur SETI watchers, pick up a strange transmission aimed at the far reaches of space. Led by Dr Amanda Tucker, the group comes to the conclusion that this is an extraterrestrial message. After hearing rumours of the UFO encounter, Tucker heads for Scotland, where she meets and after a fortuitous meeting she joins forces with Drake. After uncovering some of the truth behind the events, they are reluctantly recruited by NATO commander Reece (Fred Ward) (who believes the transmission to be terrestrial rather than alien) to decipher its meaning.
Meanwhile, RAF personnel race to hunt down and capture the downed UFO pilot and recover his craft. Equipped with alien technology, including a cloaking device, the pilot evades them (despite being wounded by a pursuers) but he finally stops a motorist, who takes him to hospital. Once located by the military and stripped of his strange garb and apparatus, the pilot is found to be none other than Tyrell, who refuses to communicate with his captors, even though they assume him to be a test pilot for a foreign nation's air-force. Meanwhile Tucker's associate, computer wiz Nick Shay (Paul J. Medford) discovers that the signal sent by the alien craft has in fact been intercepted and jammed by another force, and he suggests that they might be dealing with two distinct alien races who may be in conflict with each other.
Episode 2: "The Fourth Dimension"
As NATO attempts to analyse the alien landing pod, the danger that Tyrell poses to Earth becomes apparent when, during examination, he is found to have a tracking device in histooth. Before it can be removed, a strange portal opens, apparently attempting to capture him. During the ensuing gunfire, a policeman is killed, although the gunfight also reveals that the invaders are physical entities who can be harmed. Thinking that the enemy power is trying to rescue him, Tucker rips out Tyrell's tooth, but this allows the portal to home in on her instead and she and a number of RAF personnel are drawn into another such portal, vanishing into the beyond.
Tyrell is Taken back to the base, is interrogated, but gives nothing. The NATO commander of the base, Maj. Gen. Reece, is open-minded as to the pilot's reasons, while his 2i/c Sqn Ldr Helen Knox, angry that Tyrell may be a British traitor in the pay of a foreign power, orders his torture.
A day later, Dr Tucker and the RAF troops sucked into the portal are returned, suffering from terrible nightmares of being tortured by strange creatures. Attempts to press them further causes terrible seizures. During the night, the soldiers who were kidnapped by the nDs attempt to escape, killing their guards. Most are recaptured but one, a NATO officer who is undergoing curious physiological changes, manages to evade capture. Amanda, on the other hand, seems fine, although she's scratched the letters "nD" into her arm, leaving a wound that seems unable to heal.
Episode 3: "Only the Dead"
Drake and Amanda, having come to the conclusion that their enemy is now extraterrestrial in origin, and that the kidnapping aliens are part of a third force unrelated to Tyrell's faction, investigate further, finally getting Tyrell to tell his story. He recounts that the alien survivor from 1944 was part of a peaceful race dubbed the "Echos", who have studied otherplanets. After being shot down during one of their surveys, the survivor is imprisoned in a lunatic asylum reserved for the handicapped offspring of the British elite. Tended to and studied by Tyrell, the high command is adamant that the traveler is the test-pilot of a V-2 rocket, chosen from the Nazi concentration camps due to his physical deformities. Tyrell is ordered to leave and the Echo eventually dies from ill-treatment, but not before giving Tyrell a key to alert other Echoes to his presence.
Tyrell, having lived with the Echoes for more than 50 years, explains that the Echoes are locked in a life-or-death struggle with an alien species (which the NATO team dub "nDs"), a race of inter-dimensional beings who harvest organic matter in order to absorb it into their machines. The nDs exist in multiple dimensions, using portals to manipulate and interact with our own reality, although they cannot survive long in normal Earth space.
Tyrell helps the RAF activate his craft and send a distress signal to the Echos. In response, a lone Echo lands in Scotland, bringing a message that its entire species has committed self-genocide rather than allow the nDs to harvest their race for their malignant ends. As a coup de grace, Tyrell kills the last surviving Echo and explains that Dr Tucker was taken for a reason: she has been genetically changed in order to become half-human, half-nD, an overseer for the nDs latest crop ? humanity.
Episode 4: "The Fall of Man"
The previously escaped NATO officer is running amok in the countryside. He drives to a reservoir some miles away, cuts his brachial artery and throws himself into the dam, where he bleeds to death. Meanwhile, Tucker and the RAF team use a signal device from the Echo escape pod as a lure to attract and capture an nD, but the attempt goes disastrously wrong—the nD easily escapes from confinement, killing several personnel and destroying much of their equipment.
Episode 5: "The Battle More Costly"
It becomes slowly apparent that the NATO officer found dead in the reservoir is part of a plan to infect a local town with an illness of alien origin. It also gradually becomes evident that the events in Scotland are part of a larger conspiracy designed by the nDs and only put in motion due to Tyrell's accidental landing on Earth. When the nDs again attempt to capture Tyrell, Drake is forced to shoot him as he is being dragged into the portal, to prevent him being taken alive. As the disease spreads through the townsfolk, portal kidnappings become more frequent, and the base personnel – ignored by their superiors and lacking reinforcements – attempt to hold off the vanguard of the nD invasion, racing to develop an experimental toxin which they hope will kill the nDs.
Episode 6: "The Shatterer of Worlds"
The nDs are kidnapping the populace in order to use them as living batteries. An amorphous mountain of alien tentacles and design appears on the outskirts of Kirkhaven, and it begins expanding, swallowing up and absorbing all the surrounding organic matter and transporting it back to the nDs' home. The Earth forces attack the structure but soon discover that conventional weapons are powerless to damage or stop it. Wishing to atone for her earlier disbelief, Sqn Ldr Knox flies a Tornado jet into the portal in order to carry out reconnaissance, but she does not return and she is presumably captured or killed. Aided by her growing self-awareness of the nD mindset, Amanda uses the data collected by Preston to discover a safe passage through the nD structure. With her guidance, Drake and Amanda fly into the structure to launch a rocket directly into the portal, in the hope of causing a chain-reaction that will destroy it. The plan seems to work at first, and Drake's plane successfully escapes from the collapsing nD structure, but the joy of the Earth forces proves short-lived?within moments a new structure rises up in place of the first, expanding at an even greater rate. Amanda now realises that the plan has failed and that there are probably an infinite number of other nD structures which can be 'folded down' into normal space to replace any that are destroyed.
With Earth's future in the balance, and the world finally paying attention, it becomes clear that the only chance is the use of ultimate force, so the Prime Minister authorises the detonation of a thermonuclear bomb to destroy all the organic matter in a 50-mile radius around the portal, in hopes that this will starve the nDs of raw materials and stop the portal from growing any larger. The defenders resolve that same tactic must be used again and again whenever a new portal appears, anywhere in the world. As Dr. Tucker's transformation continues unabated despite all efforts, she walks out to stand in the kill zone as the bomber approaches and releases its weapon. The screen blurs to white, accompanied by the rumbling roar of a detonation, as the final credits roll.