A master disk for the 1987 game Space Quest II was found to contain a significant portion of the source code for Sierra On-Line's AGI interpreter, which was used to create several popular adventure games. The code was discovered in the supposedly unused space on the disk, which had not been properly formatted before use. This blunder potentially exposed Sierra's intellectual property to competitors and customers, but it went unnoticed for decades. The discovery provides a unique insight into the development of the AGI interpreter and the games that used it.