What if the protagonist inherited a valuable item from her great-aunt that turns out to be stolen from a couple of hard characters?

Or perhaps upon the great-aunt's death, the protagonist receives a scavenger hunt letter that will eventually lead her to the valuable item the great-aunt had stashed away. She must find this item before the antagonist(s).

Or maybe the protagonist finds old floor plans for a bank that her great-aunt planned on hitting before her death. The protagonist, deeply in debt, decides to enter the family business and knock off the bank.

The box of revealing info could originate from a dead great aunt bequeathed to the daughter.
The protag could be a disenfranchised
18 year old daughter who sets out on the quest. Her estranged Mother in pursuit to bring her home. A good contrast for each to discover more of the Grandmother and repair their own relationship in the process, with the added twist below.

It would be a great twist at the end if the last person the clues lead to was her actual Grandmother.
Who is perhaps under her last husbands name to throw us off the scent. Something like Mrs Kim (unisex first name) Harding.
Great triple generation actress vehicle. How about a co-write.

The box of revealing info could originate from a dead great aunt bequeathed to the daughter.
The protag could be a disenfranchised
18 year old daughter who sets out on the quest. Her estranged Mother in pursuit to bring her home. A good contrast for each to discover more of the Grandmother and repair their own relationship in the process, with the added twist below.

It would be a great twist at the end if the last person the clues lead to was her actual Grandmother.
Who is perhaps under her last husbands name to throw us off the scent. Something like Mrs Kim (unisex first name) Harding.
Great triple generation actress vehicle. How about a co-write.

In the box are clues to a hidden stash of stolen gold that was ditched back in the 1930’s. The trail is revealed, one clue leading to another, similar to The Davinci Code. Many of the city locations that need to be visited have now become ghettos. The white grandchild protagonist must enter the world of the inner-city and befriend the black residents: an interesting contrast could be made with bank-robbing anti-heros of the ‘30s and the gang-banging rapper anti-heros of today. More subtext is the change in the city over time, and cultural attitudes that have evolved (or devolved), slang, etc. Basically a maguffin quest with flashbacks...