"We, the last unbroken remnants, vow to undo the errors of our ascendants, to make the Earth whole, the lost unlost, at peril of our own birth."
You are part of a team that has come back to the 21st from the future in an attempt to save mankind from itself. Familiarity with the television show is not necessary. Um. That kind of covers it. If I think of more, I'll come back and edit this.