The Harpies

In 2004, four 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 their mother's old school bus used in 1969 on her trip to Woodstock with a group of friends.
The flawed and imperfect sisters' trip crosses the country and introduces them to characters from Demi's past. These characters will provide the clues and sometimes the answers.
The road-trip hinges on flashback sequences from the character's collective memories of the political upheavals of the late 60's and early 70's. The ripple effects of those upheavals impacted that group and changed their lives forever!
How can they solve Demi's mystery and an uncovered conspiracy? How does an old key, a hidden map, a missing girl, a Weather Underground bombing, an unfound treasure and a couple of murders all connect?