Road Less Traveled is a tie-in novel written by Cris Ramsay and published by Ace Books in April of 2011.
From the book's cover -
"A Global Dynamics researcher has a breakthrough in her attempt to visualize another dimension. And since GD's experiments have a bad tendency to affect the entire town, Sheriff Carter heads over to check it out. What he sees blows him away. The project has revealed a parallel universe, complete with another Eureka - one in which Carter doesn't exist! But as the two worlds begin to bleed into each other and residents confront their alternate selves, Carter may be the only man who can keep both Eurekas from being destroyed."
- Takes place between the end of Season 3 and the beginning of Season 4.
- Includes a sub-plot revolving around Deputy Lupo and Fargo attempting to retrieve the stolen egg of a Thunderbird - a bioengineered avian creature that can create localized storms.