It is a mystery of pint-sized proportions, featuring an altruistic act of kindness copied straight from the film Amélie, which tells the story of a Parisian waitress who decides to change the lives of those around her for the better.

The story begins seven months ago, with the seemingly random abduction of a garden gnome from the property of a Gloucester pensioner, Eve Stuart-Kelso. After noticing its absence, the grandmother of three presumed it had been stolen, and soon forgot all about it.

Yet last week, she opened her front door to find the missing leprechaun, which she had nicknamed Murphy, staring up at her. Beside the battered garden ornament lay a tightly wrapped parcel, containing an album of 48 photos showing him engaging in daring activities at exotic locations all over the globe.

Murphy was pictured abseiling down a mountain, standing in the mouth of a shark, swimming and riding a motorbike. Immigration stamps from the 12 countries he had visited – including South Africa, New Zealand, Australia, Thailand and Vietnam – were also attached, proving the authenticity of the trip.

The gnome's abductor also left a note, written from Murphy's perspective, explaining the reasons for his prolonged absence and detailing the trouble he had incurred at the hands of bothersome customs officials. He wrote that sitting in Mrs Stuart-Kelso's garden all day had given him "itchy feet", and that he had left to seek adventure in other parts of the world.

The note read: "I came to the conclusion that the world is a big place and there is more to life than watching the daily commuter traffic, and allowing passing cats to urinate on you. There have been high points, low points and positively terrifying points. But I have survived."

A group of young men who feature in some of the photographs would appear to be those responsible for the prank, but the identity of Murphy's guardian and travelling companion – who is referred to only as "The Bear" – remains unknown.

The globetrotting stunt was copied directly from the 2001 film Amélie, starring Audrey Tautou, in which the eponymous heroine's father also has his garden gnome abducted. After receiving similarly exotic pictures of his absent ornament, he realises what he is missing out on in life and embarks on a world tour of his own.

Mrs Stuart-Kelso, who works as a tour guide for the Civic Trust, described the dramatic return of her ornament as the "strangest gift" she had ever received.

She said: "I just keep thinking how funny it is. It makes me smile to see all the people he met on his travels. It was a wonderful surprise and of course it's so nice to get some good news. The story really is unbelievable. It was a beautifully written letter. The intriguing thing is that someone had gone to such trouble to do this for a complete stranger," she added. Murphy is now proudly back on display in the pensioner's garden, and is unharmed apart from a pair of missing feet – an injury thought to have been suffered during his abseiling adventures.

Mrs Stuart-Kelso said that her three grandchildren were thrilled to hear of the gnome's travels, and were looking forward to giving the ornament a fresh lick of paint.

But a spokeswoman for Gloucestershire police failed to see the funny side of the prank. "Any theft of a person's property, even if it is carried out as a joke, will be treated as a crime by police," she said. "What may seem like a laugh to one person can cause distress to another."