My name is Owen Blake. The headset pressed against my ear was a familiar weight, a ghost of the paramedic gear I used to wear. In three years of volunteering, I had learned to predict the calls with reasonable accuracy. Between 7:00 and 9:00 P.M., the eager ones called—children buzzing with sugar and hope about reindeer. After 10:00 P.M. came the insomniacs, whispering so their parents wouldn’t hear. And after 11:00, those were usually pranks. Teenagers thinking they were hilarious, or a drunk college student who’d lost a bet.