The story of
Golden Sun: The Lost Agepicks up right near the end of the first game.
Golden Sunveterans will be surprised to learn that
The Lost Ageis played from the point of view of the party being chased as they try to light the remaining two lighthouses, which will unlock the power of alchemy for the world--or will it instead unlock the world's destruction?
Also, players who have finished the first game can transfer their party into the The Lost Age, either through the separately sold game link cable or through a password.