During the second week following Chester Greene's death the weather moderated markedly. We had several beautiful clear days, crisp, sunshiny, and invigorating. The snow had almost entirely disappeared, and the ground was firm, without any of the slush that usually follows a winter thaw. On Thursday Vance and I called at the Greene mansion earlier than on any previous visit, and we saw Doctor Von Blon's car parked before the gate.
"Ah!" Vance observed. "I do hope the family Paracelsus is not departing immediately. The man lures me; and his exact relationship to the Greene family irks my curiosity."
Von Blon, as a matter of fact, was preparing to go as we entered the hallway. Sibella and Ada, bundled in their furs, stood just behind him; and it was evident that they were accompanying him.
"It was such a pleasant day," explained Von Blon, somewhat disconcertedly, "I thought I'd take the girls for a drive."
"And you and Mr. Van Dine must come with us," chimed in Sibella, smiling hospitably at Vance. "If the doctor's temperamental driving affects your heart action, I promise to take the wheel myself. I'm really an expert chauffeur."
I surprised a look of displeasure on Von Blon's face; but Vance accepted the invitation without demur; and in a few moments we were riding across town, comfortably installed in the doctor's big Daimler, with Sibella in front, next to the driver's seat, and Ada between Vance and me in the tonneau.
We went north on Fifth Avenue, entered Central Park, and, emerging at the 72d Street entrance,
