CARRABASSETT VALLEY, Maine — Just like the lost boy atop Mount Katahdin in 1939, two filmmakers are in the midst of a long journey with an uncertain outcome.

Waterville native Ryan Cook hopes his project turns out with a happy ending, just like the person whose story he’s telling — Donn Fendler.

On July 17, 1939, 12-year-old Fendler was separated from his family and became lost on Mount Katahdin. He emerged from the woods nine days later after the search for him had made headlines across the country.

Cook and his film partner, Derek Desmond of Shelburne, N.H., have set out to turn Fendler’s story into a motion picture. In 2011, the duo created a documentary called Finding Donn Fendler: Lost on a Mountain in Maine 72 Years Later.” The documentary was about Cook and Desmond’s journey to find Fendler and secure the rights to make his story into a movie.

“It brought tears to my eyes,” said Dave Cota, town manager of Carrabassett Valley. “It’s as much of a story about Donn and the life he’s led as it’s a story about these two young men getting this film done.”

Fendler, now in his 80s, lives in Newport during the summer and frequently talks about his ordeal at schools and events across New England. He resides in Tennessee during the winter.

Cook approached Cota last June about filming locations for a proof of concept film. Cook explained that the proof of concept is a way to show investors and producers how the final, full-length film will look, sound and feel. The short proof of concept film is about 20 minutes long and was shown for the first time to a small group of people on Friday, said Cook.

A 40-second-long teaser trailer for the short film was released on Wednesday night.

“This will show investors that we’re good filmmakers and that we can put together a good product and to sell them on the story of ‘Lost on a Mountain in Maine,’” Cook said on Monday. “It’s like a prototype — here’s what we’re making and here’s why we’re the ones to do it.”

Cook said they raised $30,000 to shoot the proof of concept short film. He said he credits locals in helping him keep the price down.

“All of the crew and actors did everything for free. Everything was in-kind support,” said Cook. “We got donations, wardrobe stuff from flea markets, the Maine Warden Service lent us period uniforms, a couple of antique stores gave us our props and set dressing. That was all huge in making the best film possible.”

Antique cars and airplanes were used free of charge, he said. The short movie took about two weeks to film.

Because Fendler’s story is so ingrained in Maine culture, Cook said many people are very happy to help.

“Where else can you find someone willing to drive up to Carrabassett Valley from Oakland, and sit around for hours just to have an old car in a movie?” Cook said. “You don’t find that in Massachusetts. In Massachusetts, it’s like, ‘Here’s my price.’”

He said the movie has to be shot in Maine, nowhere else.

“There’s no other place that I’d want to do it or could do it,” said Cook. “It’s not only the look, but it comes down to the people there.”

The proof of concept film was all shot in Maine, though most of the scenes were shot in Carrabassett Valley instead of at Mount Katahdin because it provided easier access. Some scenes were still shot at Mount Katahdin and at Miller’s Field in Newburgh.

Cook said the generosity and helpfulness of Mainers has been wonderful, but some of those Mainers said they were sold on the project after talking with Cook and Desmond.

“This young man [Cook] came into my office out of the blue,” said Cota. “I started to talk to him and I was fascinated by his enthusiasm. He then came back in with his documentary and I took it back home and I was like, ‘Are you kidding me?’ It’s unbelievable. And everyone I showed it to said the same thing.”

Kristel Anuszewski, whose son Maguire played Donn Fendler in the proof of concept short film, said she was impressed with the crew’s attention to detail.

“I thought that it was really authentic. It was really moving,” Anuszewski recalled of watching the filming in progress. “To me, the crew took great care with details to be able to capture not only the time period, but the mood in every location. The set was perfect.”

Maguire Anuszewski, now 11, of Winthrop was one of 200 young actors who auditioned for the role of Donn Fendler. His sister, Kerrigan, 9, also played a small role as Fendler’s sister.

“It was pretty special. It was a really cool experience and it happened so quickly,” said Anuszewski.

Cook lives in Boston, where he has worked as an assistant location manager for films such as “Knight and Day,” “Ted” and “The Town.” Desmond most recently worked as a post-production assistant on the upcoming film “R.I.P.D.” starring Ryan Reynolds and Jeff Bridges.

Cook said he plans to release the short film in July, with hopes of filming the feature-length movie next summer.

“We’re looking at raising $50,000 in order to go out and do casting calls with actors and get a script done,” said Cook. “[The money is needed] for expenses, meetings in Los Angeles and starting to get people attached to the project and then finding a couple million dollars to make this project happen. I hope to have it secured by the end of the year.”

The best way to keep up with progress on the film is to check out the film’s Facebook page, Lost On A Mountain In Maine.