A Martian has crashlanded in a rural area of the United States with no memory of its home. All it knows is it came to Earth with a purpose, but it cannot remember what. Its knowledge of Earth is limited to what remains of its meme-brain, a set of genetic and cultural norms designed to allow the Martian to move freely amongst the Earthlings.
In cases where the meme-brain fails it starts to gather information as it is discovered, allowing the Martian to adjust its physiology to match that of an Earthling. However, the meme-brain is designed for short-duration use, not long-term immersion in to an alien society.
The issue with the Martians is their senses number in the hundreds, all but the six basic senses being mental. They are such an advanced species that physical and visual stimuli are only a fraction of their experiences. When the Martian crashlanded, however, and its memory was wiped, so too was its access to everything but the six physical senses. Have you ever heard the saying that when you lose one sense the other five become stronger? The Martian would experience this, but instead of one sense, its lost access to hundreds, leaving it overwhelmed.
Basically, whatever we could ever experience is nothing compared to the Martian, and as it attempts to integrate itself in to human society it'll have to deal with rather... unique issues resulting from the sensory limitations.
I don't have much of a plot thought out, but I was thinking the Martian is picked up by a woman who takes pity on it and it ends up learning from her, getting in to many comical and sexual situations along the way.