I landed in San Francisco on the Tuesday, suitcase trailing behind me and a hand-drawn and crumpled map to my friend's house gripped in my hand, and I found the book on the Thursday. After that, my trip as I knew it was over, and a whole new one began.

   I was sat in Starbucks, one of the two million Starbucks surrounding Union Square, when I noticed a leather-bound diary under a stool by the window. I'd seen no one sitting in that stool since I arrived and no one was sat in any of the seats around it; so I only had the staff to turn to, to identify its owner. I left my coffee and newspaper on the table, and bent to pick up the diary from its hiding place. Before I could open my mouth to alert the sickly-sweet teenager behind the counter about the lost property I had discovered, I noticed the engraving on the front cover: HAND ME ON, DON’T HAND ME IN. 

   Intrigued, I opened the book. 

   From flicking through the first few pages, I found the leaves to be filled with dated entries, each of which seemed to be a mix of instructions and accounts of experiences lived. Just as often as and then I... and then I... was written, a command like now walk to Sutter would appear. By now, I was too engrossed in the scrawl on the pages and the engraving on the front cover to hand the book in, so when the braces behind the counter noticed me standing nowhere near my own drink, reading a leather book I'd picked up from the floor, and asked me if I was okay, I just said yes and walked out.

   When I arrived back at my friend's apartment, I had a chance to read the first few pages more attentively. Apart from the diary entries, there was a page with a block capital scribble:

THIS IS NOT FICTION. 

IT'S STRANGER THAN THAT. 

   And sure enough, some of the entries were. They featured ideas and experiences I never imagined I'd have in my lifetime. Places I never knew existed. Activities I never thought plausible. My mind was made up - the next day, I would read one entry every morning, and live it out that day. Follow those instructions to the letter. I knew so little back then.

*

   I'd wake up in the Grand Hyatt. I'd wake up in the Clift or the Huntington, and have the taste of clam chowder and nicotine and sex in my dry mouth as I stared at a ceiling I'd never seen before. Not sober, anyway. This is where the book took me first: seducing the financial elite of the fourth richest city in the world. It's surprisingly easy, it said, for a good-looking twenty-something to find a spinster with millions of bucks in the bank just begging for some company for the night, if one waits around in a five-star hotel bar for long enough. My first few weeks in San Francisco were spent nursing a water at the bar of the InterContinental or the Palace, waiting for lonely fifty-somethings with money to burn and desires to satisfy to come and drag me away. And they always came. 

   I never had to buy dinner those days. They'd wine me, dine me, take me to shows, drown me in attention, and then swallow me whole back in their bedrooms. The next day, they'd invariably hate the sight of me and want me gone before they'd reapplied their makeup; but by then, I'd had my fill anyway.

   And as for having sex with middle-aged women, I won't hear a word said against it. I don't know if I'll ever experience anything as pleasurable as those nights again. 

   To detoxify after that near-month of debauchery, I was directed to cycle the Golden Gate bridge. Hire a bicycle, read an entry dated in mid-summer, and cross the bridge at midday. So with cheap brand-imitation sunglasses covering my eyes, my knees still weak from the copulation and a thin brown cigar hanging lazily from between my lips, I hired a bicycle and cycled to the bridge. Taking it slow to avoid a heart attack, I took in every metre of that damn bridge like my eyes were hungry sponges. I drank it in, recording it all in a brain that had never known such an experience. The cool air rushed past my pockmarked face and wound the smoke that trailed behind me into the sky in dancing ribbons, and I was revitalised. For a bridge with such a high suicide rate, it has the potential to make one happier than you could ever imagine.

   By the time I reached Sam's bar in Tiburon, I was apt to die from thirst. My legs wobbled with every step, and my arms were stiff from gripping the handlebars, and my veins cried out for their alcohol fix. I ate an entire crab and downed two pints of water before I met my first whiskey and swallowed the tongue of a Spanish girl who was passing through San Francisco Bay, having just won a campervan in Vegas. We spent the night in the back of said campervan exploring each other's anatomy, against the advice of the little leather book that told me to catch the last ferry back across the water before sundown.

   The next morning, I read the next page: Catch the first ferry back from Tiburon. Thank the locals for their hospitality.

   I could picture the grin on the author's face. It looked just like my own as I read it.

   The next month was spent in Chinatown. The biggest Chinatown outside of China. You could spend a year there, and not see it all. From all the nodding head toys in the shop windows to the delicious fishmongers, from Chinese Six Companies to the Japanese Tea Garden (where the fortune cookie was born), I ate and drank until my stomach inflated to twice its size. And never before had, and never again have, I eaten Chop Suey that tasted as good as that which I ate there, in the city of its invention. 

   Wearing jeans that were invented in SF by Levi Strauss, to supply gold miners with just the durability they required from their clothes.

   To nurse my hangovers every morning, I was directed to one of San Fran's three hundred coffee shops. Sometimes I'd boost myself with three espressos, and sometimes I'd go all out and have an Irish coffee. I don't want to go on about the inventions of this amazing Californian city, but Irish coffee is another one. This is what the diary told me, and I believe every word. Anyway, I'd sit every morning in the window of Peet's or Caffe Trieste (where it's said that Francis Ford Coppola wrote most of the Godfather trilogy), and watch the trendy and beautiful California girls strut past in the stunning morning sun. The diary informed me that I would be blown away by this view, and my eyes confirmed it.

   More rum and whiskey and sambuca and cheesecake later, my leather-bound advisor ordered me to ride a Segway down the second crookedest street in San Francisco. It instructed me to watch a film in one of the city's many old theatres. It had me eating seafood on Fisherman's Wharf, and riding those nightmarish cable cars up the steep hills.  It said I should eat at Tony's in North Beach (so named because it was once a beach, but now lies a long distance inland due to landfill), perhaps the best pizzeria in the world. It told me to bet ten dollars on the Giants, and hand the winnings over to one of the hundreds of homeless people wandering the streets. I did just that. 

   Did you know that AT&T Park is the windiest stadium in the world? It has a Giant fan in every seat!

   I can't claim that one. My beautiful tour guide told me that.

*

   And as the pages I had left to read thinned, I began to wish that there was space to add my own experiences. The things I'd done that didn't appear in my guide. Like when I visited the Castro district looking for fun-loving boys and girls (and regretted it, having feared for my life in the streets on the journey there); or the time I emptied the contents of my wallet into a homeless man's collection tin because he was hiding behind a handful of branches on Fisherman's Wharf and jumping out at unsuspecting passersby, much to my endless amusement; or when I ate Ghirardelli ice cream; or when I received a demonstration of the mechanical working of jail cell doors from a stunning drama student and watched the sun go down from Alcatraz island; or when I visited the sea lions at pier 39; or when I took a free dancing lesson in Union Square to a live brass band; or when I ate a breakfast burrito at the Cheesecake Factory that was the size of my leg...

   But there wasn't space. Right to the end, the entries took me to places I'd never even dreamed I would end up. And the book was right - if not that they were stranger than fiction, at the very least that they were better. Who needed imagination or falseness when the reality was this good? I took so much enjoyment in their contents, in fact, that it was only by chance that I noticed that the last of them was dated just a few weeks before I'd arrived in San Francisco. Just a month or so before I had stepped into this city where I now felt like I was born to live, someone else was living the life that I had been living over the past year and was writing the words that would allow me to start. 

   I felt like I had to meet them.

   I scoured the book looking for clues as to the identity of my own personal saviour. I scanned and scraped for an address, a website, anything. I even tore part of the leather binding off before I found it, written in the tiniest writing imaginable:

IF FOUND UNFINISHED, 

PLEASE RETURN TO M. TWAIN, 

CITY LIGHTS BOOKSTORE

*

   So I entered the shop, book in hand, holding it out in front of me as if to pass it to the lady behind the counter. I gazed from shelf to shelf, mystified by all the American cover art for my favourite books and puzzled by the absence of Mr Twain behind the counter, as if I expected him to be waiting for me to enter the bookstore, my tail wagging as it was. I must have looked like a child, lost in a supermarket. 

   'Can I help you, sir?' asked the assistant, looking up from her writing and smiling sweetly.

   'Erm, yes,' I replied, looking down at the book, 'is Mr M Twain here?'

   'M Twain?'

   'Yes.'

   'Mark Twain?'

   'I suppose. Quite possibly, yes.' I grinned foolishly at her, excited to hear that she knew him. 

   'Yes, we have Mark Twain. We sort our authors alphabetically by surname, so you'll find him under T.'

   I followed her pointing biro with my eye and reached a bookshelf, my heart sinking further with each heartbeat. 

   Of course. Mark Twain, the author. I should have realised. He was the one that said The coldest winter I ever spent was a summer in San Francisco. And how wrong he was.

   I hadn’t found the author of my diary. I’d just found the next step he wanted me to take.

   'Can I do anything else for you?' the assistant asked, as I stood agape in the doorway of her shop. 

   Grabbing a Twain book, along with a Salinger and a couple of good Bukowskis, I placed the little black book in my pocket, and retrieved my wallet. 'I'll just take these,' I replied, before paying and shuffling out in a near-run.

   I went to The Daily Grill, ate the best New York Pepper I’d ever eaten, and left the little leather book behind.