Poseidon's Door - Walters Jr. Dorman

"You are in the city of Poseidon... eighty-five million years in Earth's past."

Tom West was heading home to Silverton, Colorado on leave when a portal of massive power opened up and swallowed the train. The train came out the other side, 85 million years ago in the Cretaceous era. Poseidon's door turned out to be one way with new arrivals daily from across the universe and multiple timelines. There was a thousand year old society already here of aliens and humans called the Kingdom of Poseidon ruled by Queen Talia. They attempt to blend in when an old nemesis shows up in pursuit of the Trident of Poseidon that turns out to be real. Turns out the gods were aliens and the trident was an advanced piece of technology. Meanwhile a threat to the Queen emerges in Senator Remus and a power struggle ensues. Who will get the Trident first? Can the door be closed? Will they make it home?