Thomas Plotkin and his group treaded slowly in the light drizzle toward the village of Lilam — their destination following a grueling daylong hike across the northeast Indian landscape.

The 20-year-old Minnetonka native slipped on one of the wet cobblestones along the 6-foot-wide path, falling to the ground as the weight of his pack pulled him over the edge of a 300-foot drop-off and into the rain-swollen Gori Ganga River below. Despite two weeks of searching, Plotkin’s body was never found.

In a wrongful-death lawsuit filed against the Wyoming-based National Outdoor Leadership School (NOLS), Plotkin’s family contends the outdoor adventure group failed to adequately train and protect the college student before the September 2011 trek over dangerous terrain.

“This was a very preventable death,” said Paul D. Peterson, the attorney for Plotkin’s mother, Elizabeth Brenner, who brought the lawsuit on behalf of Plotkin’s estate. “It would have been a very preventable situation if a reasonable approach to safety had been taken.”

The suit, which was filed in Hennepin County District Court last month but moved to federal court this week, asks for at least $75,000 from the company, which specializes in remote wilderness expeditions to train students of all ages in outdoor skills and leadership.

The organization, which has 3,500 students per year and has had more than 233,000 since it was founded, provides training and full disclosure of the risks of each trip, said Bruce Palmer, director of admission and marketing for NOLS.

Palmer declined to discuss the case at length, but said that the organization has been in contact with Plotkin’s mother over the past two years and that it is “disappointed” that she decided to pursue a lawsuit. It’s the second of its kind involving a NOLS fatality, but the first was dismissed.

“We operate in remote areas worldwide, and we have nearly 50 years’ experience training students in outdoor skills,” he said. “We try as best as possible to help people understand the risks that are involved.”

According to the lawsuit, Plotkin, who had signed up for a semester-long course in India, underwent a five-day first-aid course at the group’s base camp in New Delhi, India, and embarked on a 30-day backpacking course through river valleys in the Himalayas. The 15-member group was accompanied by four instructors and was 20 days into the hike when the hikers had to abandon their original campsite because of flocks of sheep in the camping area. They then continued on to a nearby village although the flocks were gone before the students left. After taking a break at a tea house in a village, Plotkin’s group of five was the last to leave while the four instructors stayed behind.

Plotkin fell about 5:15 p.m., and his fellow students went back for the instructors and were then sent to Lilam to get ropes and webbing from another group. The instructors then attempted to rappel down the slope to search for Plotkin. They called NOLS directors about 6 p.m., but did not notify local officials in India or the nearby Indo-Tibetan Border Police until 8 p.m. the next day.

Plotkin’s headlamp, rain jacket and backpack were found near the river, but Indian authorities called off the search Oct. 6 and he was presumed dead. In an investigation, the Indian government acknowledged that “One never knows whether it could have been possible to find Thomas Plotkin with the assistance of villagers and [authorities] on that very day. It is therefore regrettable that the sub-divisional administration was informed late.”

Given the adverse conditions, the report added, “It does not seem proper to have trekked that path during the evening and under a light drizzle.”

Citing the lawsuit, Palmer was unable to confirm or deny the allegations. But attorney Peterson said that as the court case continues, it may become clear why the guides stayed behind.

“I would not have brought this if I felt like they had done their job and prepared Thomas and the other students for the true risks that they were facing,” Peterson said.

Palmer said NOLS has made some policy changes in the wake of Plotkin’s death, including adding a second emergency contact and revising notification of next of kin and procedures for providing emotional support to students and staff in the aftermath of a fatality.

No one was fired in the wake of Plotkin’s death, he said. The India course is still offered on the NOLS website.