The Facebook posts popped up over the weekend. Was anyone missing a friendly black cat with one injured eye? There were several reports of him showing up at homes in Oak Bluffs, but no owner stepped forward to claim him.

More than 200 miles to the north (including seven miles of Nantucket Sound), someone was searching for the cat, missing in rural Vermont. Someone who had never been to the Vineyard.

The two sides, lost and found, eventually connected thanks to social media, the Oak Bluffs animal control officer, a game of telephone and a pet microchip. By Tuesday night, the cat was back home on the mainland with his owner, Fran Hendricks.

“Here he is, he's playing with his cat toys,” Ms. Hendricks said by phone Wednesday. “He's as casual as can be.”

While Boxer’s journey from Readsboro, Vt. to Oak Bluffs is still a mystery, his journey back started at the home of Anthony BenDavid, the town animal control officer.

One of the people who found the friendly black cat wandering around Oak Bluffs brought him to Mr. BenDavid late Saturday afternoon. The cat was sweet and the weather getting cold, so the BenDavid family took him in and set him up in a downstairs playroom, away from the family’s two dogs and cat. Mr. BenDavid’s wife, Rachel, posted information about the cat on Facebook. Their five-year-old daughter, Lyla, played with Boxer and drew a picture of him. “She wanted to keep it,” Mr. BenDavid said.

Mr. BenDavid scanned the cat for a microchip and got a hit. But a call to the microchip company had the chip tracing back to a dog in Alabama. That wasn’t right, Mr. BenDavid said, and the family kept him for the night.

On Sunday, Boxer went to Animal Health Care Associates in Edgartown, which has a boarding shelter. On Monday Mr. BenDavid got a call from Second Chance Animal Center in Shaftsbury, Vt. They had registered the chip number that erroneously traced back to the dog in Alabama, and had been alerted to the pet’s discovery. But they had the right information: the chip was registered to a cat adopted from the shelter in late November.

“The staff loved him,” Second Chance director of shelter operations Shona Ross told the Gazette Wednesday. “He was actually in a condo in the front lobby so he was a greeter.”

The two-year-old cat named Boxer — he liked to bat at people as they walked by his cage — had been adopted by Ms. Hendricks in late November. Ms. Hendricks, 67, was actively looking for Boxer, who went missing Dec. 20 after slipping out an unlatched dog door.

“We were upset,” Ms. Ross said. “She was devastated.” Fliers were posted, but Ms. Hendricks said she had lost other cats over the years to wild animals in the rural area, so she thought Boxer was gone for good.

When the shelter heard from the microchip company that he had been found on the Vineyard, they called Mr. BenDavid and confirmed it was Boxer, easily distinguishable because of his unusual right eye.

“We were thrilled and just as much dumbfounded,” she said. “How did he get all the way to an Island?”

The happy news was passed on to Ms. Hendricks. “She was so blown away when I called and said I [found him],” Ms. Ross said. “I kept her voicemail.”

Boxer was a special cat, Ms. Hendricks said, noting his weeping eye. He's been checked out by doctors and is on a special diet, she said, but he is healthy and can see out of both eyes. She thought that was why he hadn't been adopted yet, because “the personality is so killer. He is so nice.”

When she heard that Boxer had been found, “I was ecstatic. I was over the moon,” she said. “I said, this is better than winning the Powerball.”

Ms. Hendricks called Mr. BenDavid late Monday. Mr. BenDavid told her where to park her car and how to catch the ferry, and Ms. Hendricks and her dog, Little Man, headed down to the Vineyard first thing Tuesday morning. Ms. Hendricks admitted she went over the speed limit in her eagerness to get to Woods Hole.

Mr. BenDavid and Boxer met her at the Vineyard Haven ferry terminal. They chatted for a bit, and Boxer, a “wonderful, well-behaved cat,” Mr. BenDavid said, walked right into a crate Ms. Hendricks brought over. Then dog, cat, and owner got back on the ferry and headed home.

“I've never been to Martha's Vineyard but now I've been,” Ms. Hendricks said. “Someday I might come back.”

The trip home was not without incident. Ms. Hendricks said it started snowing and visibility was poor, and as she hit the outskirts of Readsboro she lost control of her car, which rolled over. Ms. Hendricks, Boxer, and Little Man were all okay, though the car is a loss, she said. Boxer remained unfazed and was so quiet the paramedics did not realize he was in his carrier. When he got home he walked over to the spot where he was served food.

One mystery was solved, but another remained — how Boxer got to the Island in the first place.

“We have no idea,” Mr. BenDavid said. “[Ms. Hendricks] doesn’t know anyone from the Vineyard or anyone near here. She lives in a small community.”

Maybe the cat was a stowaway, or maybe someone thought he was a stray and picked him up, Mr. BenDavid said.

“Who knows,” he added. “Unfortunately, you can’t ask him.”

“I have no idea how he got there and he's not talking,” Ms. Hendricks said, noting that her dog door is now permanently closed. She's working on the theory that someone who lives nearby found the cat and adopted him, brought him to the Vineyard, and "he eventually just took a walk.”

“That's the only viable story I can come up with," she said. If he hitched a ride, “someone would notice. He didn't swim across....he had to cross on the ferry in a car.”

Ms. Hendricks had only had Boxer for a few weeks when he escaped, and she hadn't fully decided on his name. “All the way home I kept thinking of names having to do with his miracle,” she said. “Vinny, for Vineyard. If he was a girl it would definitely be Martha. Or Lazarus, raised from the dead.”

Maybe she would keep Boxer, the shelter's name, she said, though she was leaning toward Big Boy.

Ms. Ross also speculated that someone found him in the rural area and thought he was a stray because of his injured eye. “He’s a super social cat,” she said. “Boxer loves everybody.”

“My question was how he ended up a stray on Martha’s Vineyard,” she said. “He had quite an adventure. He traveled further — and on a boat — than some of the staff here at the shelter.”