At 4:12 on a rainy Tuesday afternoon, Rachel Carter brought her eight-year-old son into the emergency department at St. Matthew’s Hospital.

The silence in the sub-basement was deafening, broken only by the steady drip of blood flowing through the plastic tubing from Katherine’s arm into a sterile collection bag, and the shallow, rattling breaths of her dying son three feet away.

Marcus monitored Katherine’s pulse. "She’s slipping into profound shock, Lena. Heart rate is 150 and thready. Blood pressure is 70 over 40."

"Halfway there," Lena whispered, her brow drenched in sweat as she ran Katherine’s drawn blood through a rapid cell-separator to isolate the concentrated plasma antibodies. "Hold on, Katherine. Just two more minutes."

Eli looked over from his bed. Tears streamed down his pale cheeks into his oxygen mask. "Mommy, please don't sleep. You promised you were just getting my coat. You promised."

Katherine turned her head slowly on the thin pillow, a faint, heartbreaking smile touching her pale lips.

"I have your coat, Eli," she whispered, her voice fading to a delicate breath. "It’s... it’s right here..."

Her eyes rolled back, and her head fell limply to the side. The heart monitor attached to her chest burst into a flat, continuous, terrifying tone.

"Cardiac arrest!" Marcus shouted, immediately placing his hands on Katherine’s chest and beginning compressions. "We lost her pulse! Lena!"

"Keep compressing!" Lena yelled. She grabbed the newly processed bag of antibody-rich plasma, spiked it into Eli’s IV line, and opened the flow valve all the way. "Eli, listen to me! This is going to make you feel warm, okay? Stay still!"

As the golden liquid surged into Eli’s veins, the boy gasped loudly, his eyes opening wide as his body reacted to the sudden neutralization of the deadly toxin. His oxygen levels began to stabilize instantly, the gray hue on his skin slowly giving way to a faint, healthy pink.

"It’s working!" Ramirez called out, watching Eli’s monitor jump from 82% to 91%, then 95%.

"Now save his mother!" Lena cried, rushing to the crash cart.

She charged the defibrillator paddles to two hundred joules. "Clear!"

Thump. Katherine’s body arched off the gurney, but the line remained flat.

"Again! Two hundred and fifty! Clear!"

Thump.

Silence filled the room. The long tone continued to echo off the damp concrete walls. Marcus kept pumping her chest, refusal written in every line of his jaw. "Come on, Rachel. Come on, Katherine. Don't you dare leave this boy now."

Beep.

A single spike registered on the monitor.