From the publisher's website:
The past is what you make it with GameMastery Plot Twist Cards: Flashbacks. Draw one of these Plot Twist cards and reveal secret talents and remembered lessons drawn from a character’s past. These cards open up a new experience of shared storytelling, providing players with ways to suggest surprising avenues of skill and information during an adventure, getting help when they need it most. Each of the deck's 51 cards presents a different event or life lesson that the GM and players, working together, can weave into the game’s narrative, as well as related rules effects. With Plot Twist Cards: Flashbacks, everyone can help tell the story and bring their characters’ pasts into the present.
GameMastery Plot Twist Cards: Flashbacks provide a minor story-altering idea along with a few options players can either use as presented or take inspiration from to craft suggestions affecting in-game events. Every Plot Twist Card can be interpreted in countless ways, allowing players to customize and reveal secrets of their characters’ past in ways that encourage character building and help shape the game. The Game Master doesn’t need to be the only one telling stories, and now Plot Twist Cards: Flashbacks give players the tools to give their characters depth and detail like never before!