Gustava Heffner was a member of the StB (the Czech State Police) assigned to protect to Dr. Kio Marv during the Zanzibar Land incident in 1999.
She later established contact with Solid Snake, who was currently carrying out Operation Intrude F014 and accompanied him for a brief while eventually gaining feelings for him and he in return. She helped him free Dr. Madnar from his cell. While the trio attempted to cross the suspension bridge (known as the Bridge of Sorrow) that led to the detention camp where Dr. Marv was being held, they were ambushed by Metal Gear D, where Gustava was hit by a missile. Ironically, the man piloting Metal Gear was her former lover, Gray Fox.
Before she died, she gave Snake her brooch shaped in the symbol of Zanzibar Land, which was secretly the key to Dr. Marv's locker where the OILIX formula was being held.