“Um – maybe we should try the sleeping bag,” I said. My teeth were chattering. “Spread it out in the back, I mean.”

I could feel Seb shielding his emotions more strongly than ever, and I hated that I’d had to suggest this. Finally he gave a curt nod. “Yes, all right.”

Standing outside to shift stuff around in the truck made us even colder at first. When we’d cleared a large enough space, I slid into the sleeping bag first, fully dressed. Without speaking, Seb got in too and zipped it shut, his body close against mine.

The warmth was such a relief. Inch by inch, my muscles relaxed, like I’d eased into a hot bath. My mind was a different matter. I swallowed, taken aback. I’d missed this: sleeping pressed against a warm, firm body. Oh god, I’d missed this so much.

Stop, I reminded myself shakily. This isn’t Alex.

“Yes, this is better,” Seb said at last. He was lying on his side, using his jacket for a pillow; I could feel the woven material of his sweater against my hand. “Maybe we won’t be ice cubes now.”

I swallowed. “That…would have been bad.”

Outside I could see the shapes of the trees in the moonlight, their branches sparkling with frost. Suddenly I had the insane urge to slip my hand under Seb’s sweater and touch warm skin. I bit my lip and pulled my hand close against myself, trying not to touch him at all.

It took me a long time after that, but eventually I drifted off to sleep…and dreamed about my mother. She was sitting in her old chair, her green eyes focused inward on her dreamworld – the one that had claimed her from me for as long as I could remember.

I crouched beside her, dimly aware of worn floorboards beneath my knees. I frowned as I studied her. I had the strangest feeling that she wasn’t just lost in her thoughts at all, but that part of her was actually somewhere else – some tangible place. And that she wasn’t alone.

“Mom?” I whispered, taking her hand.

My heart skipped as she blinked and saw me. “Willow,” she murmured. And as her fingers tightened around mine, familiar images started to come: small-town streets with tree-covered mountains in the distance.

“What about Pawntucket, Mom?” I urged. My mother’s gaze stayed locked on me; I could sense her straining to communicate even this much.

“Mom, please! Try to tell me!” I massaged her hand between both of mine. There was something I wasn’t getting, something vital.

But that was all; the dream was slipping away. Another glimpse of her eyes…the pressure of her fingers, fading – and then it was gone.

“No – no!” I burst out.

“Willow?” whispered a voice.

I started. Seb was lying beside me, very close, his face next to mine.

“I…was having a dream,” I said. I licked dry lips as I realized that Seb and I had curled up together as we’d slept; I was against his chest, and his arms were around me. He seemed to realize it at the same time. His muscles tensed and he drew away, moving the arm that was resting over my waist.

I shifted back a little too. As if nothing had happened, I went on, “Only…it didn’t feel like a dream. It felt real.”

When I told Seb about it, he was silent. His arm under my head stayed very still, his hand not touching my shoulder. “It sounds as if we’re going to the right place,” he said finally.

The possibility that the trouble in Pawntucket had something to do with my mother had never occurred to me. But her eyes, urging me on… I let out a breath, more determined than ever to get back to my hometown.

“Yeah, I guess we are,” I said.

The silence grew heavy – and then all at once I picked up on Seb’s feelings. They clutched at my throat, raw in their intensity: a deep unhappiness that felt as if it had been there for a long time…and a yearning towards me that he couldn’t control.

I lay without moving, intensely aware of Seb’s arm under my head – and of an answering ache within myself. It can’t be for Seb, though – can it? I thought in confusion. It’s never been him I feel this way about.

My mouth was like cotton. “Well…goodnight,” I said at last.

“Yes, goodnight,” Seb echoed.

And that time, I didn’t manage to get back to sleep at all.

For over a thousand years, the Aztec pyramids of Teotihuacán had existed unchanged, connected by broad stone avenues that stretched in long, sun-drenched lines. Now these thoroughfares of the ancient city were flanked by new, hastily constructed buildings; the hawkers who’d once crowded them, selling souvenirs to tourists, were gone.

So were the tourists. Instead, Teotihuacán Eden was packed with those humans who’d survived the Mexico City quake – and with the thousands of angels who’d stayed down here too.

“You’ve got to do something, Raziel,” said Gallad in a low voice. They were standing atop the Pyramid of the Sun, overlooking the busy walled city. Just visible was the dark, fenced building where the immune were being kept. Gallad motioned angrily. “We’re having to put more in there every day. They’re mostly A2s – the angels in that zone are starting to go hungry, do you realize that?”

“I do,” Raziel said, his jaw tight. In the time he’d spent here, he’d found no answers. His only comfort was that his assassination of the Council was likely to go undetected; he’d found nothing that would give him away.

But plenty to threaten his leadership, if he wasn’t careful. The angels down here had been baying for blood – he’d spent nearly a week already trying to smooth things over, with no idea of whether he’d succeeded.

“You do know that some are saying this is because we’re not really angels any more?” Gallad demanded. “First the deaths of the Council, then being separated. They’re saying we’re the walking dead, rejected by the very world that was meant to save us.”

“Ridiculous,” snapped Raziel. “What’s happening is just a fluke. We have no proof that it’s spreading.” The humans affected, it turned out, had all come from the same rundown neighbourhood near the Mexico City centro. Their immunity could just be location-based.

The other angel’s eyes were unforgiving. “We have no proof that it isn’t spreading either. That’s the point, Raziel. We don’t know.”

Raziel thought of Pawntucket; with a chill, he didn’t answer. What was happening in Willow’s hometown was not news that he’d chosen to share with the Mexico City angels. He mentally checked off the aberrations: Kara and the other AKs. Mexico City. Pawntucket.

The only thing that linked them all was Willow.

But how? And what if Gallad was right, and this thing was spreading organically? The angels could all die, and his reign would be over before it had scarcely begun.

His cellphone went off, giving him an excuse to turn away from Gallad without responding. Bascal. About time. He spoke tersely: “What happened?”

“They’re all dead,” said Bascal with satisfaction. “And, boss, you should have seen it! What a fight – we lost over a hundred, but it was worth it. Those AKs never even had a chance.”

Raziel waited, but Bascal didn’t continue. The dolt. Through gritted teeth, he said, “What about Fields and Kylar?” Beside him, he saw Gallad’s eyebrows fly up.

“I said all, didn’t I?” protested Bascal’s voice. “Everyone in the place is gone now, I guarantee it.”

“You saw the bodies?”

“Well, not personally – but when I left, no one was alive. We took care of that, you bet.”

Foreboding pulsed through Raziel, as well as fury with himself. How could he have been so idiotic as to leave this to Bascal? “You will go back and check again,” he ordered. “If you don’t have a body, you have nothing, do you hear me?”

“We already did check again. We did it days ago, only there’s not much to see – we burned the place out.”

“Days ago?” Raziel hissed. “This happened days ago, and you’re only just now telling me? What have you been doing ever since – carousing with A1s in some penthouse somewhere?”