“Mrs. Tidings?” Della Street asked, as they started climbing up a twisting road.
Mason nodded.
“But she was in Reno. She left Monday. She couldn’t have been at your office Monday night.”
Mason said patiently, “She’s the only one who’s tried to make her alibi stretch back of Monday night. All the others presented alibis for Tuesday afternoon.”
“Well?” Della Street asked.
“Well,” Mason said. “The answer is obvious. She’s the only one who knew that he was killed Monday night. She couldn’t look ahead into the future, and know that Mattern would try to protect his ten thousand dollars by having Tidings alive on Tuesday morning.”
“That’s all the evidence you have to go on, Chief?” Della Street asked.
“It’s enough,” Mason said grimly. “The minute she told me about leaving for Reno on Monday noon and driving all night, I should have known.”
“And she’s the masked woman?”
“Yes.”