Seven terrorist groups plan to use mythos sorcery as weapons of mass destruction and hasten the arrival of the End Times. A powerful mythos sorcerer has created a new ritual that temporarily channels Cthulhu's dreams to every living mind in a region, depending on the number of humans sacrificed in the ritual. The sorcerer has distributed the ritual to the seven groups as part of a master plan not to destroy humanity but to 'enlighten' it and drive them to open worship of the Great Old Ones.
Waetla, an androgynous prodigy of occult studies and the result of a failed experiment to breed a messiah with Yog-Sothoth, similar to the Dunwich horror. Waetla murdered every member of the cult that created and raised him as a messiah. Since then, he has developed the channeling ritual. Since the turn of the millennium, Waetla has seen a rise in eschatological terrorist organizations and cults. By teaching seven of them the channeling ritual, Waetla believes they will in turn 'awaken' humanity from its ignorance of the mythos and bring about a new age.
Channeling even a fragment of Cthulhu's psyche is a murderous act that kills every participant and a number of additional human sacrifices. Anyone affected by the ritual receives psychic impressions from Cthulhu, equal to several dozen Contact Cthulhu spells, but all at once. Victims are driven mad and become violent unstable mythos tainted madmen. It requires a large amount of expensive and esoteric materials and one object with a primordial connection to Cthulhu, such as a rock from R'yleh or a sample from a Deep One. The range of the ritual is based on the number of sacrificed victims and it builds on an exponential scale. 100 sacrificed victims could affect a major city.
Tipped off by a mysterious benefactor, the investigators come across one of the seven terrorist groups and stop them. However, certain portentous dreams of the characters combined with clues from the investigation and the benefactor add up to the realization that someone is disseminating knowledge of the ritual to other groups. The player characters realize they must find and stop the person behind the ritual before humanity is prematurely 'enlightened'. Every group is in a different part of the world so the PCs begin of a globe trotting campaign to stop the Tides of Doom.
A secondary antagonist, the benefactor is a Yithian who wants to stop the ritual from spreading. It uses the PCs as disposable cannon fodder and will try to eliminate them after Waetla is dealt with, as their knowledge of the ritual is too dangerous for its liking. Until them, it links the groups together and keeps the characters on track.
Delta Green's involvement
The benefactor knows about DG and sends Cell A enough info to make them commit at least one full cell to the operation. Alphonse will not rest until this threat is stopped.
Vigilant Sons of the Scion
An obscure and minor Middle Eastern terrorist organization with ties to many other terrorist groups. Known mostly for attacking historic 'heritage' sites and museums in the Middle East and Europe, the Vigilant Sons claim to fight a war against the false history of the Crusaders, a topic that few care about or even understand. In reality, the Sons are a degenerate mythos organization that masks its actions as terrorism. Not exactly a cult, the Sons are pragmatists who use the mythos for their own advantage, similar to the Fate in that respect. Waetla has offered them more mythos knowledge if they use the channeling ritual in a major public attack. Not wanting to die themselves, the Sons have recruited a cell of naïve Islamic revolutionaries to sacrifice themselves.
An extreme environmentalist NGO, the leaders of Tidewatchers now believe climate change is inevitable and will spell the end of humanity as a dominant species on the planet. Waetla has shown them a way to survive the rising tides, by adaptation. New deep one human hybrids are being raised under their watchful eyes. The Tidewatchers misunderstand the nature of the ritual and believes it will trigger a massive flood of every coastal area in the world. The humans in Tidewatchers are willing to sacrifice themselves, as they think they deserve to be punished for polluting the world. They dream of 'wiping the slate clean' and leaving it in the hands of their hybrid children.
Church of the Ascendant Lord
A Rapture focused Christian splinter group with a charismatic 'miracle worker' as its leader, known simply as the Reverend. The Reverend is not a human, but a Shoggoth Lord under the command Waetla. Originally another extreme reactionary Christian group with ties to the US military and right wing organizations, the Church found itself vulnerable to the miracles of the Reverend. With a few mythos spells, the Church is totally insane. They actually view mythos beings as angels of the lord. The Church believes the Ritual will bring about the Second Coming and have no inkling to their role as sacrificial lambs to the slaughter.
The Arizona commune
In the Northern Arizona desert, a group of Cthulhu cultists has formed. It is a loose commune of loners, artists, and madmen touched by Cthulhu's psychic dreams but have no physical connection to the deep ones. They have been practicing human sacrifice for years and live above the ruins of an ancient Deep one city but millions of years have changed the sea to the desert. A social worker discovered their practices and paid with his life. The DG friendly discovered the shallow burial ground of a corpse and was shot by a paranoid cultist shortly afterwards.
In the mid 1980s, an unknown experimental artist was touched by Cthulhu and created several videos of his dream, 9 hours altogether. The artist committed suicide and the tapes landed in the archives of a cable TV station unlabeled and forgotten. Several years later, a broadcast engineer discovered them and became obsessed with the imagery. The engineer was fired for unstable behavior and shortly afterwards pirated the signal of several TV stations. He broadcast several segments of the footage. This in turn made hundreds of viewers susceptible to Cthulhu's dreams. Eventually a small group of them met with the engineer, who eagerly made copies of the footage and the cult was born.
The cult believes the images of R'yleh in the footage is actually a utopia that can only be found through astrology, meditation and finding the lost city of Atlantis. Each cult member and family has a slightly different belief system but they view Cthulhu as a transcendental god. They have no knowledge of the deep ones. Waetla has recently gifted them with a few bits of knowledge they needed to figure out the ritual on their own. They simply need to dig down into the Deep One ruins for the ritual materials. As skilled ritual sorcerers, they have already stored enough POW from years of human sacrifice to cast the ritual. Each member of the commune has a different idea of what the ritual will do, but they all want to see it through. Ironically, they will cast it as soon as they retrieve the materials and because they are isolated in the desert, relatively few victims will be affected by it. However, the commune has bound many mythos entities including a Cthonian. The massive worm is used to dig tunnels to the city. Once all the cultists die, the monsters will be free to cause more mayhem.