See the The Plot Engine Manifesto for explanations and background of how this works.
An adventure seed: Guilty for Greed
WOMAN_A is married to MAN_A.
WOMAN_A approaches the PCs to help her kill her husband MAN_A as she is tired of the violences he uses on her.
She can also show some bruises on her body to convince the PARTY.
The PARTY will discover that WOMAN_A has also an affair with MAN_B.
Maybe she is willing to get rid of her husband MAN_A to be with MAN_B.
After some other investigation, the PARTY will discover that WOMAN_A’s grandfather, MAN_C was a rich adventurer, died more than 10 years ago.
Voices say that his grandfather’s house is haunted but a rich TREASURE is buried within.
MAN_B is grandson to a servant to MAN_C, and knows that to access the treasure he needs the ITEM that WOMAN_A has.
At the very end, the PARTY discover that WOMAN_A was only manipulated by her lover MAN_B which was interested only to the treasure.