Avengers: Endgame had a Herculean task; to complete the story arc from Avengers: Infinity War and do it in a way that satisfied fans. The story arc that had begun in Infinity War, involving Thanos erasing half of the Earth’s population with the Infinity Gauntlet, needed to be concluded. But how? As the Avengers would soon discover, Thanos had destroyed the Infinity Stones shortly after “The Snap”. One of the ways to undo the damage was suggested by Scott Lang (Ant-Man), involving several teams of Avengers going back in time and extracting Infinity Stones from that time period.