Taxi driver David Lee Williams waited for his passenger as the man visited a grave at Monrovia cemetery.
When the man returned to the cab, "he was crying with a gun in his hand," Williams said.
The man demanded money and told Williams to get into the trunk. Then he drove to Savannah.
The Charleston Police Department is looking for information on the Sept. 7 incident, said spokesman Charles Francis.
The suspect is a dark-skinned, black male, about 5 feet 10 inches tall and weighs about 180 pounds, Francis said.
He had a short haircut and was clean-shaven. He was wearing a black shirt and appeared to be in his early 20s.
The suspect abandoned the taxi in Savannah, Francis said.
Williams, 59, said he felt like he rode in the trunk for about four hours, but he knows it wasn't that long. And the man who commandeered his vehicle stopped twice along the way and opened the trunk to check on him, the Safety Cab driver said.
Williams, who is from Yonge's Island, said he picked up the passenger near Jackson Street and drove him to the cemetery.
The suspect stopped the car in Savannah in a somewhat secluded area between two buildings, Williams said.
He told Williams to get out, then drove away in the cab.
Williams said he walked to a nearby hotel and called the police. The police contacted Safety Cab, which sent someone to Georgia to bring Williams home.
Williams, who has been driving a cab for about three years, said he already is back on the job.
He couldn't say whether the incident made him wary of his profession. "I don't have time to think about it," he said.