The Blueprints are a key item in Suikoden.
The Blueprints contains the know-how to create a powerful weapon, the Fire Spears. These plans are of extreme importance for the Liberation Army. The Blueprints were purchased from the Dwarves, reputed for creating powerful weapons.
Odessa tasked Tir and the party to go to Sarady to deliver the blueprints to a fellow named Kage. Not everyone was on board with that idea, especially Flik who judged the plans of high importance, and such a task couldn't be handled by some strangers she just met. So Odessa decided to go with them to Sarady. The plans were successfully given to Kage, which in turn delivered them to the Secret Factory.