“How’s that?” Bertha asked, suddenly rigid with attention. “Just like the sound of a truck back-firing,” I said, “only there wasn’t any truck.”

Bertha slowed the car and looked me over.

I said, “I think the place to start is back at that Tom Durham case. The person who contacted the agency on that case talked with you. Tell me about it.”

Bertha said, “She was a girl by the name of Bushnell, pretty easy on the eyes. I remember thinking at the time that it was a godsend I got her. If she’d gone to you, she’d have vamped you into taking the case without any retainer and you’d have turned the office upside down. As it was, I collected two hundred bucks in advance.”

“What did she want?”

“She said that her aunt, the only living relative, and a little bit indisposed at present on account of an automobile accident, had been seeing quite a bit of a relatively young man lately. She had an idea the man might be a slicker who was trying to talk dear auntie out of some money. This Bushnell girl had questioned the maid, trying to find out who the young man was. The aunt got in a huff, said she was fully capable of handling her own business, and didn’t need her niece’s interfering. The niece’s pretty much worked up about it. She wanted the agency to find out all about the man. She wanted something that would cramp his style.”

“Do you think she was afraid he might have dishonorable intentions?”

Bertha snorted. “She paid two hundred bucks. Do you think any dame would part with two hundred smackers to keep a guy from making passes? She’s afraid the thing may get serious. Suppose he should propose matrimony? The aunt’s rich and the niece is the sole heir. That’s the two-hundred-dollar angle, lover.”

I said, “There’s just a chance the whole thing was a plant. Did she want me to work on the case personally?”

“I guess perhaps she did,” Bertha said, “but don’t be so damn conceited. Everyone in the world isn’t thinking about you.”