Island in the Sea of Time by S. M. Stirling (1998, Paperback, Reprint)

I am a Sci-Fi nut and in the 90’s I discovered many great what-if authors. I came across this book about3 years ago and it rapidly became one of my favorites.

In a nutshell: The Island of Nantucket (and everything that is within several miles off shore, including a couple of boats and a Coast Guard ship) is suddenly transported back in time about 3000 years. The citizens have to survive in a world where there will be no gas, oil, power, phones and goods not produced on Nantucket itself. They send a ship to the UK to trade with the people there, to get food, grain, seeds…. And come back with 2 guests. One of the people on the Coast Guard ship decides that they can rule the world and sets out to do so.
If you can get past the homosexual relationship between 2 of the main characters (I do not think it was needed for the store and felt more like Sterling was attempting to please a group of readers) you will find the book hard to put down. Though the book can be a read in itself and end there, it is actually the first of 3 books, so if you like this you can continue the story.
Over all I highly recommend this to any Sci-Fi lover out there. And secretly I wish some Hollywood producer would set his sights on making this a movie or miniseries.