Here we go again!

I grabbed the wall.

In my peripheries I saw the drop, the long drop down onto the concrete boardwalk. The fall that would break open my head and end my life if I could just let go of the wall.

I heard a whistle. The guy. The damn guy that had pushed me was still standing there, grinning at me beneath his curly black moustache. "Very impressive. For one so close to the edge, your grip on this world remains strong."

He pronounced impressive as "impressif". French, or close enough. I regarded him in horror. I'd nearly been killed by a Frenchman. I wanted to move off the wall, but he was blocking me. "Hey man, what's your problem? You gotta be mad, tryna push people off walls!"

He laughed this away. He showed a lot of teeth when he laughed. "You think it is lucky for me, non, that you did not fall. I think the police would a difficult time calling me a murderer without being able to identify me." He leant into me. I caught a whiff of spiced perfume. His leer was cruel. "I think you wanted to fall. You heard the call of the void."

My heart skipped. The world seemed to shrink around the Frenchman, until there was only him, and the drop behind me. The shark and the lure. "You don't know anything about me."

"No. Only that you heard l'appel du vide. Why else would you sit there on the edge? The wall is not so wide, eh? The drop is quite long. And now you sit there, even though I have pushed you. It still calls to you. The void. The call of the void."

I felt faint. I looked up and down the wall. Surely plenty of people were sitting here. But no, I saw none. Had seen none in the long walk from the hospital. With nothing to say I said nothing, I waited for the Frenchman to tell me what else he knew.

He sat beside me, keeping at an amicable distance, giving me room to get away if I wanted to. "Then it's true. You hear it too." He glanced my way. "What's your name?"

"What's it to you?"

"Ahh, come now. You can call me Knife. Augustin Knife." He held out a hand, and with some reluctance, I shook it.

"Henry. Henry Falcon."

"You prefer Henry?"

"I prefer it to Knife."

"Henry, then. So you, Henry, are bored, wandering. Wishing there was more to challenge you. You don't believe in God. You don't believe in an eternal paradise. You know that when you die, that will be the end of you. And yet you see no reason for being alive." His eyes narrowed, he looked me up and down. "You think you are a worthless human being and everything good you could do with your life, your native greed and stupidity will spoil, and that it is the same for all people, and all life, and that life as you experience it is, simply, entertainment between meals. And so, unable to give meaning to your existence, you answer the call to oblivion."

I was silent, stunned. Yeah, and yeah, and what the actual hell?

Knife elbowed me. I could smell the river in the mild breeze. "Well?"

I exhaled my nervousness. "You put me in a tough place to argue. Two months ago I drove my sister's car off a bridge. And here I am, talking to you, when you tried to push me off this wall."

Knife regarded me thoughtfully. "Your sister, she was not in the car at the time?"

"No. No, she was at home."

"And you are just out of hospital, alone, oui?"


"Ha," he said.

Seagulls and ibises squawked overhead, blotchy brown birds in the brown haze enveloping the state of Chicago. Knife, he was almost certainly mad. But he would – maybe he alone of people could answer my questions.

I started carefully, choosing my words hesitantly. "I haven't been able to contact my sister. Her phone number doesn't work. The nurses at the hospital told me there was no such address."

Knife smiled. "Maybe you dreamed her."

"My bank cards as well. My health care card." I pulled out my wallet, ripped out its cards one by one and tossed them onto the wall between Knife and I. It didn't matter if the wind took them into the river. They were doing me as much good in the water as in my wallet.

Knife whistled. "You are in trouble. Your licence – the picture is bad enough. But that it was issued in a state which no longer exists in this world, that is terrible luck."

"What do you mean?" Chills ran the length of my spine. Like maybe I knew what the Frenchman was saying.

He leant back, only his knees keeping him from going over the wall. His face tipped to the smog-strained sun. "You're a traveller. You didn't mean to come here, but here you are. Your world must be similar, that you are not in a total panic. Do you realise that you are on the wrong world?"

I could only shake my head.

Rocking forward, Knife thumbed a business card from his vest pocket, passed it to me. "I work for an organisation known as the IDA. The Interdimensional Detective Agency. I'm on this world on business, but ah," he glanced at his watch, "perhaps an allowance can be made. Tell me, before you came here, what did you do?"

"I, I," trying to process this. The slippery feeling of madness. The business card was cream, perfunctory. Smaller than ordinary. In fourteen different character sets was printed what I assumed was the same line. IDA Agent Augustin Knife, BUD. I handed it back. "That's nicely crazy. I was in the army. Obviously you were in the mad house."

Knife shrugged. "I can help you or not. It is your choice. But beware you will not find your family on this world. As similar as this world may be, one small change in the recent past has altered the course of everything since."

I stood to leave. He was too far from me to stop me now. "And you expect me to believe this? Intergalactic Detective Agency – other worlds – man, quit wasting my time."

"Henry, wait!"

I didn't wait. I walked away. Towards the cafe with its red umbrellas out the front and the mouth to the underground arcade.

Knife grabbed my arm. I spun and shoved him away. He slapped me. I staggered, my ears ringing, and he started at me savagely. "Will you listen! You know in your head it makes sense. Did you find your sister, huh? Did you find her? Any sign of her?"

My ear! That guy slapped like a cow in a hurricane. I feigned calm like I was gonna answer him, and when I saw him unwind half an inch I slammed my fist into his jaw. He fell back a pace, and instead of turning on my heel and running, I pounced on Knife and the two of us went flailing to the stones. Knife got on top of me and boxed his fist against my jaw. I grabbed his fist the next time he took a swing, dragged him down close and bashed my head into his.

Bad idea. Stars sparked in my vision, pain burst behind my eyes. Groaning, Knife rolled away. I sat up to clutch my head, my hands coming away bloody when I peered at Knife. Blood oozed down his forehead. He caught my eye. He flashed teeth in what might have been a smile.

"Die like a dog, fight like a man. Is that your policy, Henry?"

I groaned. Struggled upright, pulling Knife up after me. "Is that a problem?"

"Au contraire. I like it." Knife grinned. Together we limped to the café, where the patrons stared at us in unabashed horror as we helped ourselves to a seat beneath a red umbrella. Knife waved to a waitress. "Two coffee, eh? Some biscuits too, if you will."

"None for me," I said. "No money."

Knife ushered the wide-eyed waitress into the café. "Don't listen to him. I will pay." He glanced blearily at me, serviettes pressed to his forehead. "So you got no money. No clothes either, I suppose?"

Although my head hurt, I felt better for having half beat the shit out of someone. "You suppose right."

Knife snorted. "Then I tell you what. Let me buy you a coffee and proper clothes. Let me tell you about the Interdimensional Detective Agency. I promise you, I will let you go if you are not interested. And then you can try to find your sister and wander around lost here forever if it pleases you."

What did I have to lose? Surely not my sanity.

"About two thousand years ago," said Knife, "a planet of psychics discovered a means of travelling to another reality of their own world. That is, their own world in a parallel reality. In these worlds they found many strange things, from people who possessed no psychic power to people with great technologies, worlds where plants had developed sentience, and worlds with no life whatsoever. From the few who returned to their own planet, the people learnt that travel to and from dimensions was possible. We call these early pilgrims the Void Jumpers, for the method they used to change worlds was to answer the call of the void.

"It took many centuries, but at last the Void Jumpers found a planet whose population had technology far enough advanced to create permanent doors to other worlds. No longer did the travellers have to depend on the whim of the void to take them to a habitable world. However, the nature of finding new worlds was still random. A Void Jumper would take the leap into the void, and from that end use a type of algorithmic key to access their home world. Soon there were hundreds of worlds discovered, and a small number of sentient beings who were aware of the capability of travelling between worlds.

"Interdimensional tourism became popular. This was some seven hundred years ago. The more worlds tourists travelled to, the more worlds became aware of interdimensional travel. Problems soared. Primitive civilisations were getting their hands on technology they had no hope of using safely, warlike populations could access weapons, planets were stripped ruthlessly of resources, smuggling of sentient children and exotic lifeforms was on a scale you can barely imagine. That's when the BUD – Board of United Dimensions – was formed. BUD held a number of conferences between all sentient species it had thus encountered, and created the Interdimensional Travel Convention, a series of rules governing all travel. It's when people break the rules that the IDA is called in. We agents act as spies on some worlds, others monitor a number of places and deal with crime as it crops up."

Knife leant back in his comfortable café seat, coffee foam staining his moustache. Bloody napkins coated the plastic tablecloth. "As you can imagine, pursuing crimes across dimensions is a complex and demanding job. There are not nearly enough of us to cover the worlds we have discovered, and more worlds are being discovered all the time. Most agents, such as myself, take on world-spanning cases solo. Tell me, Henry; do you really desire to return to your world?"

I didn't really desire anything aside from Knife to slow down and tell the entire story again so I could figure out exactly where I'd lost my mind. I had the unfortunate suspicion it had been about the line "a planet of psychics".

"It would be nice."

He nodded to the bridge. "My priority is my mission here. However I would be happy to take you along with me, if you please. Who knows? Maybe you'll want to join the IDA."

I shrugged. "What's your mission?"

"I'm on the hunt for a fugitive by the name Aleci Jin Baxter. On this planet he goes by the alias Ace Jagger. He's the technical man for a group of punks called the Daggers. Ace is a smuggler. He managed to escape BUD when his smuggling ring was brought down two years ago, and we've been hunting for him ever since. Now he's in my sector, he's my man. I have no intentions of letting him escape."

Images flashed through my mind. Afghanistan. A mission. Opening fire on an insurgent stronghold. Stuff I'd never done, needed to know if I could do. "You think I could help?"

Knife nodded. "If you can stay alive. But I take it you are a survivor."

"It doesn't matter to me either way."

"Does it bother you if I die?"

"What do you mean?"

"Well," Knife hunkered forward. From his curly black moustache to his beige suit and that undeniable air of villainy about him, he was so... damn... French. "I don't wish to die. Unlike you, I have a goal. As such, I would prefer my life continue a little longer."

I nodded. "Understood. I won't do anything to put your life in danger."

He waggled a finger. "Unnecessary danger. Necessary danger is perfectly fine."

From the cafe, where Knife paid with cash, we strode into the mouth of the underground arcade. Here we found clothes stores, every one of them a homage to three decades previous. In blue jeans and a white T-shirt I looked nominally less mad than I had in the hospital gown.

"C'est genial," Knife protested when I pointed this out. "Besides, you'll only need them for a day or two. With any luck we'll have Ace in custody tonight."

We left the arcade for the plaza, stepping into a gaudy red-shaded world, courtesy of the brown smog. Cars buzzed on the bridge. Knife led the way to the red steel bridge, talking about different worlds, talking things I couldn't understand. It felt like a dream. We reached the low stone wall I had so recently contemplated throwing myself off. Here, nearer to the bridge, a stone staircase led down to the boardwalk. There were a few people about, it was late afternoon. We descended the stairs and I dreamily watched the fall recede, lessen from death, to injury, to inconvenience as the stairs flattened.

"Another agent left something here for me," Knife was saying as we fell under the shadow of the bridge. "A bag. It will be in the wall."

The wet, putrid stench of the brown river wafted around us as Knife ran his hand along the wall, checking each crack and bump in the stone. Finally his fingers hit a lump and the lump sprang out at us, falling out onto the concrete boardwalk with the ringing sound of tin, though it looked enough like stone.

Knife tugged a navy blue duffle bag from the wall. He passed it to me, replaced the tin capping. I shouldered the bag. Heavy, but nothing compared to our EOD gear.

"We'll take the train into meet Ace." Satisfied, Knife led the way back to the stairs. "How do you call it, the metro."

"I'd call it the subway."

"Really? Fascinating."

We hit the stairs. Knife first, me lagging behind, watching the water, watching the boardwalk retreat. An inconvenient fall becoming an injury. An injury becoming a death.

Yet I had thought as much about the bridge I'd driven Brandy's car off. That the fall would probably kill me. And here I was, talking to a Frenchman who claimed he was from another world. That he was a space-time detective.

Knife was already at the top of the stairs. "Hey, Henry!" he called. I tore my gaze from the river. "You coming with me?"

"Yeah," I said, turning away from the water. "Yeah, I am."