Taken from Wikipedia.org:

The player's character is a postal clerk in the small fishing village of Festeron. The cranky postmaster, Mr. Crisp, orders the player to deliver an important envelope to the proprietor of Ye Olde Magick Shoppe. The proprietor in question, a kindly old lady, then asks the player to rescue her cat from a mysterious sorceress known only as The Evil One. Stepping out of the store, the player finds that quaint Festeron has mysteriously been transformed into a more sinister town called Witchville. There are but a few hours to defeat The Evil One. Fortunately, the player soon finds the Wishbringer, a magical stone that can grant seven wishes if a suitable object is used in conjunction. To see the future, for example, the player must be wearing glasses and holding the stone. The seven wishes that can be granted by the stone are for advice, darkness, flight, foresight, freedom, luck, and rain. Each wish can only be used once per game, and requires that the player possess some related object.

A player can solve Wishbringer by using the wishing stone, then play it again without using it to get a higher score. A few Infocom games has puzzles with multiple solutions (for example, the “Loud Room” from Zork). However, Wishbringer has several such puzzles, many of which can be solved either in a straightforward (that is, non-magical) manner or by using one of the stone's wishes. The game can be successfully completed without using any wishes: At the Congratulations screen, the game informs the player of this fact, if the player had used any wishes. Conversely, it is impossible to finish the game using all of the stone's wishes (wishing for flight invariably causes the game to be lost.)

Wishbringer#Plot_and_gameplay