who is "Dagger"
Clutching the shoulder strap of his portable radio, Youngblood wriggled his hips, forcing himself farther back. He was grateful that Johnson, long- legged, had told him to slide the front seat to its forward position. They were going to be cramped enough in the rear as it was. Swiveling around, he saw Halfback swinging after the Lincoln. He called to Jacks, "Follow that car." Then he signaled Varsity over his set: "Dagger to Daylight"— Daylight was Agent Kivett's code name—"I'm shifting to Charlie. Do the same."