The Clue Hunt[]
The Clue Hunt has been going on for over 500 hundred years, since the time the orginal Gideon Cahill had taken his serum and divided it into 4 serums, the Janus, the Lucians, the Ekaterinas, and the Tomas.
Then Grace Cahill came along five hundred years later and was able to piece together all of the 39 Clues, creating the master serum. Instead of taking it, she hid them around the world, leaving vague hints and following her ancestors hints also.
When she died, she set in motion this plan for her grandchildren and several other teams (Ian and Natalie Kabra, Alistair Oh, Irina Spasky, the Starlings, and the Holts) to find all the clues, and become the most powerful person in the world. She hoped to unite them by doing so.
Thus the hunt for the 39 Clues was born.