I got off my bike in Lower Marsh. It was dark and drizzling. At the entrance to a side street a man with a hood up against the weather pointed me towards a railway arch. As I approached I could just make it out through the gloom.
I locked up my bike and stepped inside an enormous entrance tunnel. Neon lighting emitted a low-level glow, and at the distant end, a projector threw shimmering images at the wall.
The vaults beneath Waterloo station are impressive. A labyrinth of dimly-lit Victorian brickwork soundtracked by the low-frequency rumble of trains above.
It was used for offices until relatively recently, but the five vast vaults are now a dedicated arts space.
The same group that brought the celebrated Rooftop Film Club to London has rebranded as Underground Film Club and made the venue their home for the next four weeks.
The space has been transformed into an underground cinema complete with a bar, a pie shop, a popcorn dispensary and the organisers have obtained a huge bank of tiered seating - apparently on loan from the graffiti artist Banksy.
Thanks Banksy. Thanksy.
At the bar I met my friend John, a journalist and out-and-out film junkie. He was excited.
"I'm going to have an Aperol Spritz," John said.
"What the hell is that?"
"It's a Prosecco cocktail. I think."
"I'll have one too."
A PR person for the event was at the bar. "Do you have cameras?" she asked us.
Neither of us did. She had brought a GoPro for some reason.
The barman who'd spoken earlier spotted the little camera.
"Look at this." He said in an Italian accent. "I was wearing a GoPro when I did this."
He turned to reveal a severe curved scar looping across the back of his head.
"I crashed my bicycle coming down a mountain. I smashed my face. They took the bone from here," he waved at the scar, "and put it here," pointing at an unblemished cheek. "But it was a great film."
"It's a good story." I said. "I'm a cyclist too. But mostly in London."
"It's too dangerous in London," he replied, shaking his head.
After a couple more drinks - a mojito and a beer, the pie stall began to become a very important part of the scenery.
I opted for a lentil and spinach pie. It came with an unexpected helping of delicious mash and gravy. John had a meat pie.
The event was sponsored by Bulmers' Live Colourful campaign. I don't drink cider. But the Bulmers people had made some sort of instant photo-booth that took four pictures of you, and then performed, in the words of the rep, an "Andy-Warholisation" upon it. I stood in front of it, and then out of a little hatch plopped a picture of me, rendered in four different colours. That was unexpected.
But we were really here for the cinema. The film, which I'd seen before, was Wes Anderson's The Grand Budapest Hotel. I'd liked it first time round, and was prepared to like it again.
We went to our seats with a couple of beers in hand. Above us, the trains rumbled.
But the trains were not going to disturb the film, as every person on their way into the cinema was handed a pair of wireless headphones.
They had a volume dial, and worked perfectly. I even kept them on when I went to the lavatory, and only at quite some distance was there any interruption.
Anderson's quirky caper was an excellent match for the unusual venue. I suspect most people had already seen the film and were here purely for the cinema itself.
I found that second time round, the film was even better. This was heightened no-doubt by the impression the venue had made on me. I felt less the passive consumer - and more of an active adventurer: 'Here I am, underneath Waterloo train station, drinking cocktails and watching a quirky film. I'm the sort of person films get made about.'
It's a simple idea, and it works well. When I spoke about it afterwards it certainly wasn't the film I was excited about.
The experience is perhaps so good that it will directly impact any assessment of the film shown. For the film junkie this is pure manna - a dependable drug.
After the film finished, the bar remained open for another hour or so. We had one more drink, then left, back down the neon tunnel out into the drizzle.
I thought about the barman's skull, and decided to take the train home.