A new psychotropic drug recently made its appearance on the streets of New York City. From the yuppies to the homeless, everyone is getting addicted to it (easiness of finding, cheapness, fashionable appealing). What the customers don't know is that this drug, aside from its chilling and tripping effects, is also a way to open up their minds and make them dream about R'lyeh in order to create a strong magical field upon all the city, from which the evil cultists (member of the above-mentioned international conspiracy, see previous posts) can barrow the amount of MPs necessary to complete a certain ritual (OPEN TO SUGGESTIONS) and contact (OPEN TO SUGGESTIONS). Three days ago the DEA Police planned a raid in the biggest reputed factory of this new drug, (SOMEWHERE, OPEN TO SUGGESTIONS). It ended up with six dead officers, and one dead drug dealer. (Actually an infiltrated; the police haven't still shared this information because they have two others, and they don't want the public opinion to know about this. So, it's up to the characters to find it out.)
In a public conference, they said the raid failed because of a tip, but really some of the DEA officers were also involved in the conspiracy, and shot the others in the back. The coroner has collected evidences that proof this, but is afraid to share them (most likely received some kind of pressure). She will try to contact the characters in order to receive some help, just because they appear to be out of the conspiracy (she doesn't trust any policeman in service). She will be probably killed at some point before she can reveal too much (who said Hounds of Tindalos? Ah!) so that the players will now they are on something.
On a side-note, think of the international conspiracy as some kind of reversed Delta Green. They can stop the characters bank accounts, make them appear as criminals, even delete all their records so that they officially "never existed".