“A heron,” Jem confirmed.

Years before, Jem had enchanted a silver pendant in the shape of a heron and pressed it into the palm of a young woman with Herondale blood. A young woman in danger, who steadfastly refused his help.

With this pendant, you can always find me, he had promised, in the silent voice with which he had once spoken. Jem had been Brother Zachariah then, still bearing the robes and duties of the Silent Brotherhood, but this mission—and this promise—had nothing to do with the Brotherhood. Jem was still bound by it, would always be bound by it. I trust you will summon me for help, if and when you need. Please trust that I will always answer.

The woman he’d given that pendant to was a Herondale, the last heir of the lost Herondale, and the silver heron meant that after all these years, she needed him. As Jem and Tessa watched, the bird traced letters of fire on the air.

I turned away from you once, but please help me now. I thought I could do this on my own, but the Riders are closing in. If you will not come for me, come for my boy. I thought I could buy his life with my suffering. I thought if I left him, he would be safe. He is not. Please come. I beg you. Save me. Save my child.

—Rosemary Herondale

The light winked out. Jem and Tessa were already in motion. In the century and a half they’d known each other, much had changed, but this truth endured: when a Herondale called, they would answer.

L.A. traffic wasn’t as bad as everyone said. It was exponentially worse. Six lanes, all of them nearly at a standstill. As Tessa inched forward, shifting lanes every time a space opened up, Jem felt like he was going to crawl out of his skin. They’d Portaled from France to Los Angeles, but the closest location that was familiar enough to them for the Portal to work was halfway across the city from the source of the distress call. Magnus had reached out to his network of West Coast acolytes and secured them transport to get the rest of the way. The turquoise convertible didn’t exactly scream “incognito,” but it was enough to carry them the handful of miles from Echo Park to Rosemary Herondale’s house in the Hollywood Hills. The ride should only have taken a few minutes. It felt like it had been a year.

I turned away from you once, but please help me now.

The words echoed in Jem’s mind. He’d spent decades searching for the lost Herondale—finding her, finally, only to lose her again. But after she’d refused his offer of protection, he’d made her a promise. He would come when she called. He would save her when she needed saving.

I thought I could do this on my own.

James Carstairs would always come to the aid of a Herondale. He would never stop repaying the debts of love.