The Harpies

In 2004, four flawed and imperfect sisters embarked upon a cross-country road trip to fulfill a promise to uncover a long-buried tragedy in their mother Demi's past. They went on the journey in an old school bus used in 1969 on Demi's trip to Woodstock with a group of her friends.
The sisters' journey introduced them to characters from Demi's past, and those characters provided the clues and sometimes the answers to this mystery.
The story of the road trip hinged on flashback sequences from Demi's friends' collective memories of the late 60's and early 70's political upheavals and the ripple effects of those upheavals that impacted that group and changed their lives forever!
How could they solve Demi's mystery and an uncovered conspiracy? How did a hidden map, a missing girl, a Weather Underground bombing, a kidnapping, an unfound treasure, and a couple of murders all connect?