"Evening, Stratos." This was a voice I hadn't heard for a while, a voice so authoritative that anyone hearing it for the first time would never imagine its owner was homeless.

"Angelino," I replied, looking at my screen and noticing that he had changed his number yet again. Angelino never phones unless I've asked him to get me some information, the kind of information only Angelino can dig up. But this time I hadn't asked.

"You did say if I ever needed anything ..." he said.

I sat back down on the bed. "When do you want to meet?"

"In an hour?"

Any minute now Maria would be coming down to my room. We hadn't seen each other for days; her wishes, not mine. And I felt the need to be with her and far away from other people more strongly than ever.

"See you then," I said, my phone wedged between my ear and my shoulder as I tried to get a head start on the unpredictable Athenian traffic by dressing as I talked.

We always let down those we love most. And we always take the gamble that they'll understand. I told Maria something urgent had come up. When you've been with the same person since you were teenagers, you don't need a great many words to communicate; sometimes you don't need them at all. Her belly was already beginning to swell – she had just entered the third month, but her baby seemed to be in a hurry to get out and spend time with us. I refer to it mentally as "her baby" because I didn't know, and didn't dare ask, if it was mine. There were two reasons for this: first, even if it wasn't mine, I would love it as my own; the second reason was that I thought about the possibility of it being mine every single day and felt that happiness such as this was beyond my grasp, and I didn't know how to handle it. Maybe I just didn't deserve it.

I got into the Peugeot and set off for the Ambelokipi metro station. I have made a mental note of all the side streets round all the stations in a thirty-minute radius of my flat where it is possible to park. I use different stations all the time so I don't become an easy target. In my line of work, being able to move around unnoticed is a major advantage, and standing at six foot three and weighing in at slightly over two hundred and twenty pounds, almost all of it muscle, I'm automatically at a disadvantage. Fortunately, most people who use the metro look straight down. And only down. It's as though they've had all curiosity for the world erased by the financial crisis.

I'm a caretaker – that's my job. I cater to such dark desires that a good many of my clients look shocked as they listen to themselves articulate those desires. Not so shocked, though, as when they try to convince me that their target deserves to be taken down. Years ago, one very rich lady, who tried to hire me to take care of her business partner, called me a "maverick" when I explained to her that my investigation showed that everything she'd told me about him was a lie and that I would keep the deposit as agreed but wouldn't be going ahead with the job. Most people who hire me don't really believe I'm serious about my terms and conditions.

In a way they are right; they pay a lot of money and expect their instructions to be followed and their victims taken care of, no questions asked. But not by me.

When you're the best, you can afford to be a maverick.

This was not my city. It was something else, something sick trying to look, sound and smell like Athens. But it was failing and it knew it, just like the old juggler I used to see around this time of day in the middle of the square. He would lose track of one ball after another but always bent down, picked them up and kept going. Because there was nothing else he could do.

The good thing about Omonia Square was that it had not waited for the devastation of the last three years to go to seed. The state it was in surprised no one. It had managed to descend into darkness much earlier than that, as though it had seen the crisis coming and the path the country would take and wanted to get ahead of the game. Any neighbourhood you walked through in Athens, there'd be a surprise waiting for you: where there had been a shop you were greeted by a sturdy lock; where you'd once seen the postman inserting letters into the individual letter boxes that line the entrance halls of every block of flats in the city, you now saw the mail piled high on the floor by the main door, next to the outstretched body of some homeless person wrapped in a blanket, resting on the front steps of the building. But in Omonia this sort of thing came as no surprise to anyone. They were familiar sights and had been for a while. Omonia had become the only part of Athens where you knew what to expect, morning, noon and at night – especially night. Certainty can be very reassuring, if depressing, especially when everything unexpected that happens in the city seems to force reality further into a downward spiral. But in Omonia, as the old song goes, "you can't get any lower than this".

It was almost 9.30 p.m. It was completely dark and conditions that spring night in February were close to perfect for all types of vampires to come out – both those that drink their own blood, scouring their legs for a vein to stick the needle into, and for those who go round exploiting the needs of others. The escalator took me out of the station next to a hoarding advertising a new department opening inside the Hondos Center department store, where customers would unlock all the secrets of chocolate. On the pavement outside the shop, a dark-skinned Asian man was kneeling down, sobbing, with jets of blood spurting out of his cheek. He'd been stabbed; a friend was trying to help stem the flow with a piece of paper. Like most people, I walked on.

For most of the last twelve years, Angelino had lived right there on the square with Hector, his very sweet, very large geriatric German Shepherd, who walked with great difficulty. Hector had disappeared one night last winter. Angelino explained at the time that very loyal dogs take themselves off when their time has come, to spare their owners the sight of them dying. Their owner is their family, and their family must not be made vulnerable by their death. The next time I saw Angelino, he was all alone in his usual spot on the square, and I asked him why he didn't get another dog. "If I did, it would mean that Hector was replaceable," he answered.

We weren't meeting at Angelino's usual spot. He'd moved. I was walking quickly, not just to make sure I got there on time, but to escape the stench from the side streets, which had been turned into public conveniences and sites of infection. I passed kiosks groaning under the weight of porn mags; Nigerians selling knock-off designer handbags and watches; Chinese people selling energy bracelets and ointments promising to heal all wounds and cure all cancers; Georgians on the corner of Agiou Konstantinou Street, asking me if I "wanted some"; Kurds magicking cartons of contraband cigarettes out of nowhere; girls and boys of all nationalities offering up any and every part of their bodies for between ten and forty euros to any sex-starved passer-by, and multicoloured used condoms left behind after each quickie; dilapidated buildings with people piled ten high into studio flats of no more than three hundred square feet. If instead of the ten olive trees the municipality had planted to symbolize the ten tribes of ancient Athens they had planted one tree for every race...