The family of a man who died of a heart attack on a Carnival cruise ship alleges in a lawsuit that he was barred from disembarking while the ship was docked and forced to die a painful death as the ship sailed to its next destination.

In the lawsuit filed Tuesday in Miami federal court, Jeffrey Eisenman’s wife and two adult children, who were all on board the Carnival Sunshine last December for a family cruise, accuse the crew of negligence and infliction of intentional emotional distress.

"Jeffrey Eisenman died onboard while confined to the medical center of the Carnival Sunshine against his will," the lawsuit alleges. "His family was forced to watch on in horror at his mistreatment and decline into a gruesome death."

Jeffrey Eisenman, 65, sailed on the Carnival Sunshine out of Cape Canaveral, Florida, on Dec. 1, 2018, according to the lawsuit. On Dec. 3, at about 1 p.m., as the ship was docked at Grand Turk Island in the Caribbean, he began to feel ill, his family said.

An hour later, the ship’s doctor diagnosed him as having suffered a “major heart attack” and said he would need a stent implanted in his heart, according to the lawsuit.

His wife had purchased travel medical insurance that included coverage for air evacuation if necessary, the lawsuit claims.

Just before 4 p.m., when the vessel was scheduled to depart for its next destination, Puerto Rico, the ship doctor told the family that Jeffrey Eisenman would not be able to get off the ship because someone else had to be medically disembarked first, the lawsuit alleges. The family says they "begged and pleaded" to get off the boat, but the captain ordered the departure for Puerto Rico.

"Despite their many cries for help, Carnival utterly failed the Eisenman family and disregarded the life of a critically ill human being," the family said.

When the boat docked in Puerto Rico, the lawsuit states Carnival’s staff could not guarantee Jeffrey Eisenman's body would get to Pennsylvania, where he lived, from the island, which was still recovering from Hurricane Maria.

His wife and daughter disembarked in Puerto Rico, while his son stayed on the ship to accompany his father's body to its final destination in Cape Canaveral, according to the lawsuit.

Carnival denied this characterization of events.

“We are very sorry for the Eisenman family’s loss, but the scenario that is alleged in the lawsuit is not accurate,” Carnival Cruise Lines told NBC News on Thursday. “Our onboard medical team followed all proper procedures to attend to a guest who became critically ill very quickly, including liaising with the local hospital which was not equipped to handle his condition. Mr. Eisenman’s treatment plan and keeping him on the ship was formulated in consultation with his family.”

The Eisenman family is seeking damages for loss of support, loss of inheritance, funeral expenses and court costs, among other things.