It takes a special kind of dog to leave a warm house and race into howling winds and torrential rain to rescue its owner.
Zeus, a young labrador-retriever, is certainly special – he's one of 16 guide dogs shortlisted in this year's Guide Dogs Annual Awards, celebrating the life-changing powers of these amazing pooches.
The Guide Dogs for the Blind Association, known as Guide Dogs, is a charity that has been helping transform the lives of blind and partially-sighted people for more than 80 years, by training dogs as skilled companions and guides.
Guide dogs are taught to help people with a range of other health conditions too – like brain tumours and autism – by assisting with daily chores, helping them interact with the world and giving them freedom and mobility.
Janice Heatherington, who lost her sight in a road accident, had only known Zeus for six weeks when he heard her distant cries for help and came to her aid.
In the early hours of last New Year's Day, the 79-year-old had nipped to the bin outside her Hampshire home in her dressing gown. It was stormy and she became disorientated and wandered away from the house.
Nobody was around, but despite being a pup and only a trainee, Zeus sprang into action.
"I used the 'come' command, and out he trotted," recalls Janice, who had to loop her dressing gown belt around his collar so he'd go into work mode.
"I didn't know where I was, so I told Zeus to 'find home' and we walked quite a way, but he did find home.
"I was frozen solid. If Zeus hadn't come out, I firmly believe I could have come down with hypothermia, I was so cold, and wet through."
This remarkable tale may be the reason he's shortlisted, but for Janice, Zeus is a hero every day, as he enables her to live more confidently and independently.
"Having a [guide] dog makes all the difference in the world to me," she stresses. "Zeus is wonderful and I'm so proud of him."
The winners will be revealed at a lavish star-studded event in London tomorrow .
Zeus is nominated in the Beyond the Call of Duty category, and his is just one of many heart-warming stories highlighting the huge benefits guide dogs bring.
Maggi Burgess and her guide dog Annie have been shortlisted for the Inspirational Guide Dog Owner award, which goes to an owner who's achieved something exceptional or overcome a significant challenge.
After being diagnosed with a tumour five years ago, Maggi, 55, was left partially-sighted.
She explains: "When all this happened to me, my confidence hit rock bottom and I didn't go out on my own at all for 16 months.
"But I realised I couldn't go on like that, so I applied to Guide Dogs and was lucky enough to get Annie. She's changed my life completely."
Maggi's ambition was to simply get to the shops on her own, which she managed after Annie's arrival three years ago. "Now we just go anywhere," she says.
She started playing bowls and takes Annie on the bus and train to matches.
"Annie has boosted my confidence and allowed me to get out and about on my own," she adds. "She loves being fussed over, but the minute her harness goes on, she knows she's working."
But the black labrador has some quirky characteristics – including hating water.
"If there's a puddle, she'll guide herself around it and lead me straight through it. She's a real diva," says Maggi, laughing.
Richard Llewellyn, the guide dog mobility instructor who nominated Maggi and Annie, says: "What Maggi wanted to achieve by getting a guide dog is something most of us take for granted – just popping down the road for milk and bread.
"But by achieving her goal, Maggi perfectly illustrates how dramatically someone's life can change when they lose their sight, and just how much of a difference having a guide dog can make."
A dog has certainly made a difference to the life of 12-year-old Abigail Lewis, who has been shortlisted in the Young Persons Achievement category.
Abigail lost her sight when she was three years old, when a brain tumour suppressed her optic nerve. She now has Ursula, a buddy dog (dogs who haven't quite made it as a fully-fledged guide dog but who work as a companion, usually for younger people to get used to looking after a working dog).
Ursula helped transform Abigail from a shy girl who was reluctant to go out, into a youngster who's happy to explore her local area with her four-legged friend.
Her treatment has intensified recently and Ursula has helped her through the tough times, which included chemotherapy last year.
Last month, Abigail, who lives in Staffordshire, was told her tumours are stable and she doesn't need chemotherapy for at least another six months.
"When I heard I'd been shortlisted, I didn't know what to say. I'm really happy and proud," she says.
Her mum, Sara, adds: "Being shortlisted has really cheered her up, and given her something to take her mind off her illness."
The awards will be hosted by television and radio presenter Adrian Chiles, while other big names involved include actor Martin Clunes, singer Camilla Kerslake and blind MP David Blunkett.
Guide Dogs spokesperson Louise Robertshaw says the awards are to "celebrate everything that's great about guide dogs – it's like a great big warm hug".
And she explains her charity does much more than just provide specially trained canines that help people with getting out and about.
"We're about making sure people can live the lives they want to live."
For more information or to make a donation, visit: www.guidedogs.org.uk