Dan is an out-of-towner, who reluctantly bought a summer home up on Highland Lake. He is one of the patrons trapped in the Grocery Store when the town outside is engulfed by the Mist, and becomes one of David's group.
He unsuccessfully attempts to stop Norton and his group from leaving, suggests the idea of a gun, and is part of the expedition to King's Pharmacy. During the expedition, he is killed when a Gray Widower cocoons his entire body in its webs. His body is dragged off by the Gray Widower into the parking lot.
It is physically uncertain whether or not Dan is an out-of-towner or a local in the film, but the latter is suggested as Ollie Weeks knows him well. When the Mist appeared, Dan and John Lee Frovin entered the Mist as it spread across Bridgton, where they were attacked by an unseen creature which knocked Dan down and killed John Lee.
Dan retreats out of the advancing mist to the Food House, screaming about his encounter in the Mist. He quickly calms down when the doors are closed, though. He brings up the idea of a gun and using lighter fluid and mops to make torches when David's group are discussing defenses.
Dan takes part in the expedition to King's Pharmacy the next day, and escapes back to the market with five of the others. The next day, after he and the rest of David's group are cornered by Mrs. Carmody and her followers, he, armed with a hammer, fights to protect himself and his friends, particularly Billy and Amanda, from them and after Ollie guns down Mrs. Carmody and effectively destroys her congregation and stops the attack, successfully escapes the market to David's Land Cruiser. He, along with the others, keeps driving south through the Mist until the Land Cruiser runs out of fuel.
Dan and the rest of the remaining survivors decide to instead be shot by David so as to spare them a more violent death by the creatures. Their deaths are apparently in vain as a military rescue convoy arrives moments later.
Dan is shown to be a logical and generally pleasant character, despite having little to no faith in humanity whatsoever.