In times even earlier than Earth's prehistory existed a callous, warlike race known as the Jagaroth. These creatures have deep green, roughly-textured skin, with a single green eye surrounded by thick green lashes in the center of their heads. The Jagaroth have no obvious mouths, only two fringled flaps on the sides of their heads. And they clad themselves in metallic silver armor, making them a truly fearsome sight.
But, to the relief of the universe, the Jagaroth destroyed themselves in a massive war. At least one ship escaped the destruction - crippled, it made planetfall on primeval Earth in the middle of what would eventually be the Atlantic Ocean, but the land was uninhabitable. With their atmospheric thrust motors disabled, and no secondary engines, their only resort was to try engaging the warp engines from the planet's surface - an untested technique which proved to be unwise. The ship was able to lift off from Earth's surface, but when the warp engines were engaged, the ship itself warped and exploded.
Amazingly, from this disaster, there was one survivor - the Jagaroth who had been in the warp field, with the lives of all the others in his hands. Scaroth, last of the Jagaroth, was flung into the time vortex and fractured into twelve parts. These splinters of his being were scattered in time - all identical, yet none complete. These included a prehistoric human, who invented the first wheel and showed the true use of fire; an ancient Egyptian, who was apparently hailed as a god and caused the pyramids to be built; an ancient Greek or Hebrew, who was probably responsible for the mapping of the heavens; a Norman soldier; a well-dressed man of indeterminate time period; Captain Tancredi, who lived in 1505 Florence; probably a splinter who was acquainted with Shakespeare; and Count Carlos Scarlioni, who lived in 1979 Paris. These splinters all lived independent but connected lives throughout Earth's history. They appear to be constantly aware that they are splinters of a whole, but they are not always fully aware of it. Only when the interface of the time continuums is unstable, and perhaps also during dreams, do the splinters truly commune with one another, calling out the name of Scaroth and declaring that they shall undo the centuries which separate them. Exactly how this communication occurs is never revealed. The individual splinters seem to be able to temporarily resist the call of the others, but it ultimately proves too alluring and they cannot resist any longer. When this happens, the splinters hear the voices of all the others. They become disoriented and refer to themselves in the plural; it is as if they are not fully aware of their identity until the other splinters break through into their consciousness, at which point they become manic about their identity and their goal.
Scaroth's goal is the one thing which motivates him. He is consumed with survivor guilt, as he is the only surviving member of his race and was the one who pushed the button which consigned the other surviving Jagaroth to oblivion. His one overriding ambition is to travel back in time to the point at which his ship was destroyed and persuade his past self not to press the button to send the ship into warp.
In order to accomplish this, Scaroth's splinters throughout history push humanity forward to provide Scarlioni with as much technology as he can possibly have in the year 1979. He regards this as having brought up a whole race from nothing in order to save his own. The technology that he is eventually able to build, with the help of one Professor Kerensky, is a cellular accelerator, more colloquially called a time bubble. Within the accelerator, an egg can be turned into a fully-grown chicken in thirty seconds. Count Scarlioni persuades Kerensky that the goal of this research is to end world famine. But his true aim is to use the bubble as a time machine. He hopes to put the entire world into the bubble and regress it by 400 million years; and his attempts to do this succeed in pushing the world back in time by two seconds, causing time to momentarily jump a groove and repeat itself. But this poses a problem: the bubble itself does not travel in time, it only goes forward or backward within its own lifecycle. One can have two adjacent time continuums running at different rates, but without a field interface stabilizer, it is impossible to cross from one to the other. Basically, Scaroth would be able to send the world back in time, but without a stabilizer, he would not be able to be there himself to save his ship. The time bubble would only be able to regress him to a baby or kill him of old age.
Of course, all of Scarlioni's researches into time travel required immense amounts of money. In order to finance his experiments, his earlier splinters were able to hide priceless works of art within the Parisian château he would eventually own. These included several Gutenberg Bibles, the long-lost first draft of Hamlet and six Mona Lisas, painted by da Vinci himself at the behest of Captain Tancredi. Scarlioni released these treasures onto the market one by one, discreetly, although the sudden influx of lost treasures did attract some attention. His most masterful crime was in stealing the real Mona Lisa from the Louvre in order to supply seven potential buyers with what they each believed to be the genuine article.
In order to accomplish his plans, the Count made use of a wide range of Jagaroth technology, including a sonic knife, advanced holographic imaging, and a prismatic field which changes the refractive index of the air, deflecting alarmed lasers from around priceless works of art and thus rendering them vulnerable to theft.
Scarlioni is assisted in his schemes by his beautiful wife, the Countess. He equips her with a Jagaroth bracelet capable of scanning an entire area and projecting it holographically through a device, down to details as small as the security systems of a room. The Countess is wilfully blind to Scarlioni's true nature, diverted by fur coats, trinkets, and the nefarious excitement of their life together. But when the Doctor points her folly out to her, she begins to realize that she has seen things she cannot explain - such as an Egyptian scroll depicting the Jagaroth as one of their gods. Having realized her error, the Countess confronts her husband with a gun, and asks him what he is. Scarlioni, who usually keeps his true face hidden under a mask which splits down the center when removed, reveals his true Jagaroth visage to her. He then uses a control on one of his rings to send a signal to the Jagaroth bracelet his wife wears, killing her.
Scaroth is certainly not averse to killing anyone who stands in the way of his goal. He will not kill simply for pleasure, but he refuses to allow anything to threaten his plan to save his race. However, he does not only kill for serious transgressions - even a slight mistake is sufficient for him to decide that someone is not worth keeping in his employ. Accentuating his offhand killing techniques is his very suave manner. Scarlioni, at least, is very much the charmer, although if angered, he can easily fly into a simmering rage.
He is also not above destroying the entire city of Paris by blasting it through an unstabilized time field, when he learns that Romana has the knowledge to stabilize his time bubble. His threats, and his pleas for her to help him save his people, work - Romana constructs a field interface stabilizer for Scaroth, not realizing the consequences of her actions.
As the Doctor realizes, in this instance, helping a race to survive is not such a noble goal: it was the destruction of the Jagaroth ship that supplied the massive dose of radiation necessary to cause the birth of life on Earth. If Scaroth stops the ship from exploding, he will cause the human race to never have existed at all. Scaroth, of course, is completely aware of this, but as he has groomed the human race for this one express purpose, as the tools of his salvation and nothing more, he has no compunctions about destroying them for his aims. Fortunately, Romana had built the stabilizer to only work for two minutes, after which Scaroth would be pulled back into the present. When Scaroth leaves, he rigs the display to blow up, forcing the Doctor, Romana and a violence-prone detective named Duggan to track him by following his time trail in the TARDIS. They arrive in prehistoric Earth just before Scaroth, who is knocked unconscious by a well-placed punch from Duggan. With Scaroth sent back into the future, the Jagaroth ship explodes as before, and life on Earth is assured. Upon Scaroth's rematerialization in the château, his butler Hermann is terrified by his Jagaroth form, and hurls a brick into the time bubble. This disruption causes it to explode, destroying Scaroth and setting the château on fire. One of the seven Mona Lisas escapes the fire, and is (re?-)hung in the Louvre.
