It's nearly two hundred years in the future (the year 2197) but Earth has regressed, not advanced. A series of wars and bids by power-hungry dictators made up a period called the Disintegration (2163-2175). After the Disintegration, Earth became one giant super-country. Geographical segments are under control of their own governments, like before, but they can be likened to local councils of today, with no real authority. As a result, travel is easy, and the world's cultures mingle like never before. International relations had been pushed forcefully by governments before the Disintegration - partially contributing to the Disintegration by angering some extremist groups - so between this and the newfound freedom of movement, the corners of the world are closer than ever before.
Remember how I said Earth had regressed, however? Many of the world's greatest minds were sought out and killed during the Disintegration, and much technology was lost or destroyed. By 2197, the world is starting to pick up momentum once again, but science, in particular, was hit hard by the Disintegration, and is still at a 2030-esque level. That's not the worst of it, though. The governmental system is controlled from a secret location by an enigmatic band of . . . people. But they're not important right now.
What is important, however, is that these guys are uber-corrupt. That is, they're only interested in extending their power. So as a result, the world is screwed. The international (using the term for convenience) police force is rotten to the core, and crime is rampant; so much so that they've had to bring back the Wanted posters. There are no laws regarding weapon possession, and being a mercenary is a popular trade. There are thousands of these rogues spread around the world, and anyone who knows where to look can hire them as assassins, bodyguards, security etc. (So in a nutshell, the world is seriously screwed up.)
One of these mercenaries is a man named Joseph Hart, alias Romulus, a solitary soul. Joseph gets a call one day from his brother, Victor, a professor at Ilium University, near Rome, about an urgent scientific expedition that he needs help with. Being a brotherly kind of guy, Joseph agrees, and the pair of them shuttle off to South America (beating off a few thugs/natives along the way). Buried deep in a cave far beneath the Amazon, they find a large crystal. Victor is ecstatic and the pair immediately return to Italy, Joseph wondering what in the world his crazy little brother could be up to; Victor remains mysteriously silent as he retreats into his lab to study the crystal.
A few days later, Victor asks for Joseph's help again. He explains that inside the crystal has been sealed a spirit - the spirit of Cerberus, a monster of Ancient Greece. Joseph scoffs at this until Victor explains the results of his research. Thousands of years ago, these monsters - Cerberus, the Chimera, the Sphinx, Fenrir, the kappa etc - actually did plague their respective civilisations, but they were all sealed away inside these crystals by a power or powers unknown. (This is because although the monsters' bodies can be destroyed, their spirits could not.) These crystals were scattered to the furthest corners of the earth and hidden far from the eyes of mankind so that the world might be safe from them.
Joseph is still sceptical until he witnesses Victor 'extracting' the spirit from the crystal. The spirit manifests in the semi-corporeal form of a three-headed dog before whooshing through a wall and disappearing. Disappointed, Victor explains that when the spirits are freed from their crystal prisons, they will immediately seek out a human body to possess. When the human's body is occupied by the monster's spirit, their consciousnesses (ugly word) battle for control of the body. If the host is weak-willed, the monster may take over completely, turning them into little more than a hollow, bestial shell of a person. If the host has an iron countenance, they may be able to dominate the monster's spirit and seal it away deep within their mind. This requires great luck, however, and probably forewarning, which cannot be given as it is impossible to tell who the spirit will possess. What usually happens, though, is that there is a compromise of sorts. The host's personality becomes more like that of the monster occupying them, and they gain superhuman powers because of it. The hosts are often mentally unstable.
When Joseph challenges Victor about how he knows this and why he's so obsessed, he receives no definite answer. Instead, Victor injects him with a drug that allows him to mysteriously home in on the running Cerberus spirit and locate its new host. (This was concocted by examining the bizarre chemical makeup of the crystal Cerberus was imprisoned in.) Reluctantly, Joseph manages to master his newfound ability to locate Cerberus. He and Victor trace down the host (in Sweden or something, I dunno) and grab him. Cerberus' power manifests, and the guy trashes half of Victor's lab with living shadows or something.
His doubts growing, Joseph demands an explanation from Victor as to why he wants this. Victor reveals that he wants to use the super-powered humans to take down the world government. Joseph realises his brother has gone crazy and tries to leave, but Victor stops him, explaining further. He's not the bad guy, he says. He wants to make the world a better place, not a worse one. The government they have now is dooming the world even further, he purports. If he and his monster-men were to replace them, he would be able to bring the world back to it's pre-Disintegration glory, with one key difference: it would still be one nation, with him and Joseph at its head.
Joseph leaves, slightly worried, but confident that his brother will go no further without his support.
A month or two later, there is news of a terrorist attack on a local government. Joseph pays it little attention - this sort of stuff happens all the time, after all – until he hears that it was apparently carried out by individuals with 'magic powers'. He realises that Victor has had more success than he expected, but still does not want to get involved. He can't see it escalating to a level that might threaten him or his livelihood, and besides, who would want to go up against his own brother? He's no wannabe action hero, at any rate. So instead he tips off someone who has experience in the matter: a university professor of ancient history.
The professor convinces him to fight, and Joseph reluctantly allows himself to be convinced, realising - as the violence escalates and hundreds of innocent people are killed - that Victor a) has a greater chance of success than he ever imagined, and b) is completely nuts.
Now, Joseph's mission is to track down as many remaining crystal-monster-spirits as he can and convince them to join his cause before Victor gets to them. And if they can't be convinced, then . . . well, Joseph will have no problem disposing of them. He has to assemble enough forces to take down Victor's rapidly growing army of possessed humans, and he has to . . . get along with them. Overcoming all the odds, as well as time, bad guys, and his own anti-social attitude, Joseph is racing the clock for the sake of humanity. And he's not even sure why he's doing it.