You are the High One of the Kingdom of the Sargalo. You are in your palace on the isle of Lapour. The kingdom is in great danger and only you can save it. You must learn about this peril and find the way to resolve it.
Notes
Although sometimes referred to on sites as Adventure to Atlantis the actual title of Apventure to Atlantis is clear on the game's animated intro screen and the cover of the game.
Included RPG elements; you start the game by dice-rolling your statistics.
Looks like more an Ultima-like RPG than a classical adventure game.
Forgot to add: you can find in the Apple II TOSEC from 2009-10-31 in Games section.