Room 13, Hotel Santo Domingo, Mexico City

I'm writing this sitting on the bed with the talisman in my free hand. The ceiling fan's wobbling and the overhead light is flickering. The shadows slicing the walls are making me dizzy.

I didn't sleep on the flight from Heathrow or from Jamaica and I won't sleep tonight. A cicada is rasping, he's quite extraordinarily loud. I've searched the whole room but I can't find the little bugger. He could be anywhere, cicadas are brilliant ventriloquists.

I know what you'd say about getting to sleep, Dr Walker, but I can't take one of your pills. Early flight tomorrow to some little town in the mountains, then a charter plane to the jungle and a boat up a river. I don't know its name and I don't want to. I just need to get away.

I never told you about the talisman, did I? It's the size of my thumb, neatly shrouded in my handkerchief. After I'd had the first coffee with her we were saying goodbye under our birch tree when her hair snagged on a twig and she pulled it free. When she'd gone I went back and retrieved several long black strands and snapped off the twig and wound them round. I've had the talisman ever since. I keep it zipped in the breast pocket of my safari shirt, against my heart. I don't care if that's sentimental. I will keep it always.

Just now I wrote that I have to get away, but I know I can't do that, not ever, because she's dead. I can never get away from that.

You see how it always comes back to her, Dr Walker? That's why I can't sleep. That's why I've done what you suggested and started this journal. And maybe you're right, maybe writing will stop the thoughts going round and round like angry wasps.

Although I'm not going to write about Penelope. Why should I? No point re-hashing the past. This is about the future. A clean break.

I found that cicada. He was hiding behind the picture of the Virgin Mary above the bed. He's been driving me mad and when I found him, I wanted to squash him. Me, the insect lover! I was shocked.

Of course I thought better of it. He is so beautiful. Some kind of Zammara, I think. His transparent wings are deceptively delicate, folded over a powerful body that's boldly marked in turquoise and black. How can I blame him for disturbing me when all he's doing is trying to attract a mate?

Some hope in here, poor sod. I've stowed him in my pocket, I'm going to take him outside and find him a home. I spotted some oleanders on the corner of the street. Who knows, maybe he'll even find a female.

One thing's for certain. I can't stay in this room any longer. It's supposed to be winter in Mexico but it's hot as hell and the walls feel as if they're closing in. I can't stand this bloody flickering.