My eyes dart left and right, ever alert to danger. I stop and listen. The only sound I can hear is my thudding heart.
But not for long.
A scuffling noise followed by a blood-curdling screech pierces the night air. Stumbling towards me is a mass of decaying and rotted flesh. I stand rooted to the spot. "Run," I hear someone shout. As the zombie figure lunges forward arms outstretched, my fear-paralysed legs finally respond, escaping by the skin of my teeth.
Welcome to 2.8 Hours Later, an adrenalin-pumping cross-city chase based on the format of a live action movie or computer game. Participants - like you and me - are the heroes and heroines of the piece, while a cast of actors and volunteers play zombies, police officers, underground operatives and government agents.
The world's largest touring street game - whose name pays homage to the cult British zombie movie 28 Days Later - visits Edinburgh this month followed by four Glasgow dates in August. The exact location for each game is kept strictly under wraps until a week before.
Created by Bristol-based games designer Slingshot, the adventure begins in what is dubbed "Asylum", a sanctuary safe from the roaming hordes of zombies. But resources are dwindling. Our mission is simple: leave Asylum, break into the city, find fresh water and make it back alive. Armed with a map, the goal is to unlock a series of puzzles to progress to the next stage. That quest is made all the more challenging - and thrilling - by the presence of zombies along the way.
Rather than the traditional biting, those players caught are marked with UV ink which denotes "infection" with everyone later scanned to discover who will be transformed into the undead - courtesy of Slingshot's make-up artists - before heading to the zombie disco. On paper, it sounds straightforward enough but the reality is far more terrifying.
The organisers arrange us into groups. There's nine in mine including Paul Ingram, 18, a bar worker/chef from Birmingham who is dressed in a Slipknot T-shirt and black rubber gas mask. "I'm an adrenalin junkie so this is my kind of thing," he says. "I enjoy being scared. I love anything to do with gore and the undead. My favourites are definitely the George Romero films. I'm old school."
We make our way to nearby "Terminal" and follow the instructions given in our briefing to hack into the computer mainframe and obtain a grid reference. The code flashes up on the screen. We're on our way.
Rounding a corner into a small cul de sac we encounter our first lumbering, foot-dragging undead. I immediately run around like a headless chicken. It's an early inkling that I'm perhaps less Sheriff Rick Grimes, the hero of the hit TV series The Walking Dead, and more random extra that gets killed off in scene two.
A series of checkpoints and further codes lead us to the reservoir where sterile water can be procured. It is heavily guarded. Police officers patrol the confines alongside menacing-looking sentries toting machine guns.
Suddenly there's a flash of torchlight from the nearby trees. A mysterious figure in army fatigues beckons. He's a sympathiser to our cause and knows how to sneak in. Moments later we are crouched down, attempting to scurry stealthy round the parameter towards a tarpaulin-covered tank.
Our chosen water carrier is Cammy Craig, 30, from Dunfermline. His precious cargo can't be infected so the rest of us may need to become collateral damage in order to secure the success of the mission. Which isn't exactly what you want to hear when faced moments later with a gauntlet of wailing, blood-splattered undead blocking your path.
I've always had a soft spot for zombies. In the supernatural world vampires are the aristocracy. They are the cool kids smoking down the back of the school bus: sexy, hip, and untouchable. Zombies are the bottom rung of the ladder schlubs - even lower down the pecking order than mutants. Zombies are a club anyone can join.
Which is perhaps why I've long preferred them to the fang-toothed gang. Or rather did. I'm rapidly changing my mind. While the earlier zombies in the game were slow, lethargic creatures, this latest batch are quick on their heels. I barely make it through. Five of my group are caught and "bitten".
It's all starting to unravel. We've only just caught our breath when the next knee-knocking challenge looms: traversing a tightly packed storage warehouse where potential danger lurks around every corner.
Miraculously, the entire group emerges unscathed. But my own luck is about to run out. Another pack of zombies impedes our passage. In the melee which follows I get separated from my team-mates. I hear a spine-chilling wail inches from my ear and take flight.
My pursuer is so close I can feel hot rasps of breath on the back of my neck. I zigzag across the road, twisting and turning, but to no avail. Finally, lungs close to bursting, I can run no more. I turn to see a zombie in a diamond patterned golf jersey, her hair and face crusted with blood. Game over. Wah, wah, wah, waaaah.
While the exhilarating appeal is easy to understand, according to writer and director James Wheale, who devised the storyline for this year's event, Survival, there is a much deeper meaning behind the concept of 2.8 Hours Later than people simply scaring themselves witless for fun.
He views it as a way of "sticking two fingers up to at the Tories" for their role in "drastically reducing the number of arts programmes going on in cities". "The whole notion of the game is trying to reclaim dilapidated parts of the cities, such as industrial areas, as play spaces," he explains. "Zombies seemed the most logical outreach for an artistically drained environment."
Beforehand, Wheale imparts some sage wisdom for a wet-behind-the-ears rookie like me. "Getting chased hell for leather is great fun and definitely one of the best parts of the game, but there are numerous ways to solve each piece of the puzzle," he says. "Keep your wits about you and think intelligently about each zone. You can use your brain as much as your legs."
Sadly, my legs are wilting fast and the infection would appear to be ravaging my brain. I get caught twice more. My fate is sealed when we reach the UV scanner. My hand is stamped: "Infected". Three of our team survived, six were lost. The good news is our mission was a success. I would like to hope that future generations in Asylum will talk of our brave sacrifice.
The zombie disco beckons. Nothing left to do but party like it's the end of the world.
2.8 Hours Later is in Edinburgh next Friday and Saturday followed by Glasgow on August 15-16 and 22-23. Tickets start from £28. For more information, visit 2.8hourslater.com