Belder raised astonished eyebrows. “You lost her, Mrs. Cool?”

“That’s right.”

“But I made certain that you were on the job. That your car—”

“That part of it was all right,” Bertha said. “I got on her tail, but I couldn’t stay there.”

“But, Mrs. Cool, surely — I should think it would have been absurdly easy. She certainly had no suspicion she was being followed.”

“What makes you say that?”

“Because — well, I’m certain she didn’t.”

“I’m not half that certain, myself,” Bertha said. “She either pulled a fast one, so damn fast that I still don’t know exactly what it was, or else I’m the victim of a mighty peculiar series of coincidences.”

Belder’s voice showed distinct irritation. “In either event, Mrs. Cool, the result, I take it, is the same. We have lost all opportunity to bring this poison-pen letter home to Mrs. Goldring.”

Bertha said crisply, “Let’s see that letter again.” Belder hesitated a moment, then took it from his pocket.