Assassination-ish Stories

There will be a book called the History of Snails, written 98% by my friend, that goes with this. Set fifteen years from today, there are two sisters who are serial killers. No one knows who they are, but they call themselves the Disposers. They are trying to take over the world by killing off all the world wide leaders, which explains the name they call themselves. They are not trying to show any animosity towards those that they murder, but it just seems that way. They will not be described to you, for their safety, as you may have seen them or know about them before their murdering phase. Anyway, the CIA, FBI, SWAT, NCIS and all the other worldwide agencies are trying to find them...