He found another trace higher up. But on the second flight there was no mud at all.

Somewhere in the back regions a bell was ringing. Landis hurriedly retraced his steps to the front hall, followed by Bernard. Here Landis paused to whisper to his companion.

“Allen had to see Anita to make their stories agree,” he hazarded. “That’s pretty plain.”

“Or Isabelle or Miss Mount or Joel Harrison—for some other reason!” teased Bernard. “Either Harley or Joel may have left those traces, don’t forget! You can’t be sure until you measure them!”

“Huh! Allen sneaked up to talk to someone, while we were questioning Russell!”

“Maybe!”

The local policeman lumbered out of the library, at the orders of Sergeant Forbes, to answer the bell. The door opened to admit a man with a camera, a tripod and a suitcase. Landis advanced to meet him, held a brief consultation in an undertone and led him into the library. They came out together, the new arrival carrying the Japanese bow, the blunted arrow and the shaft of the broken arrow which had pierced the quiet body in the front room. Bearing them in a gingerly fashion he vanished into the dining-room opposite. Landis rejoined Bernard.

“Finger-print expert,” he explained. “When we’ve seen the girls and Joel and cleared the library, he’ll examine the armor and the door and take photographs. Now what?”

“Anita Harrison!” Bernard suggested grimly.