Look for stuff on the Nizari/Hashashin, it's a captivating story.

http://en.wikipedia.org/wiki/Hashshashin

http://www.alamut.com/subj/ideologie...etymolAss.html

Bibliography
Spoiler Alert, click show to read: 
Lewis, Bernard (1967). The Assassins: A radical sect in Islam. New York: Basic Books. ISBN 0-465-00498-9.
Burman, Edward (1987). The Assassins. Wellingborough: Crucible. ISBN 1-852-74027-2.
Daftary, Farhad (1990). The Isma'ilies, Their History and Doctrines. Cambridge: Cambridge University Press. ISBN 0-521-37019-1.
Daftary, Farhad (1995). The Assassin Legends: Myths of the Ismailis. London: I.B. Tauris. pp. 88–127. ISBN 1-850-43950-8. "Review"
Franzius, Enno (1969). History of the Order of Assassins. New York: Funk & Wagnalls.
Hodgson, Marshall G.S. (1955). The Secret Order of Assassins: The Struggle of the Early Nizârî Ismâʻîlîs Against the Islamic World. The Hague: Mouton. ISBN 0-8122-1916-3. http://books.google.com/books?id=C3c...sassins&pgis=1.
Maalouf, Amin (1989). The Crusades Through Arab Eyes (translated by Jon Rothschild ed.). New York: Schocken Books. ISBN 0-805-20898-4.
Polo, Marco (1903). H. Cordier. ed. The Book of Ser Marco Polo, volume 1 (3rd revised translated by H. Yule ed.). London: J. Murray. pp. 139–146. http://books.google.com/books?id=vsKY2uImEiEC&printsec.
Silvestre de Sacy, Antoine Isaac (1818). "Mémoire sur La Dynastie des Assassins, et sur L’Etymologie de leur Nom". Memoires de sins, et sur l’Institut Royal de France 4: 1–84. "English translation in F. Daftary, The Assassin Legends, 136-188.".
Stark, Freya (2001). The Valleys of the Assassins and Other Persian Travels. New York: Modern Library. ISBN 0-375-75753-8.
Willey, Peter (1963). The Castles of the Assassins. London: George G. Harrap.
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