The "piece" you might be looking for is the at the end: Laura Oliver (whose real name is Jane Queller) is revealed to have been the one who secretly provided the gun used to kill her own father, Martin Queller, during a conference in Oslo decades earlier. Key Plot "Pieces"
If you're looking for a specific , there is also a Wattpad story titled "PIECES OF HER - Piece 1" that uses similar phrasing. Pieces of Her (TV Mini Series 2022) Pieces Of Her
: A random act of violence at a diner forces Laura to use lethal skills she’s kept hidden, which goes viral and alerts people from her past to her location. The "piece" you might be looking for is
: Much of the plot revolves around a lost cassette tape that could incriminate Jane's brother, Jasper, in the Oslo events. : Much of the plot revolves around a
: She spent 30 years in witness protection to hide from Nick Harp, the leader of a radical group and the biological father of her daughter, Andy.
: Laura is actually Jane Queller, a former concert pianist and daughter of a wealthy pharmaceutical mogul.
If you're referring to it is most likely the Netflix thriller series starring Toni Collette or the bestselling novel by Karin Slaughter that it's based on.