He could hear one man say to the other that it was only a couple of drunks, and saw them turn back and go out of sight.
Chick sang another verse, and then both listened.
There was an answer, indistinctly, yet clear enough for them to hear every note. They heard the third verse of the song sung through.
“Ida’s here,” said Chick.
“Are you sure?” asked Nick.
“Sure!” replied Chick. “I’d know her way of singing in the wilds of Africa.”
“Then you have found her,” said Nick. “And the next thing is to get to her.”
On looking up, he saw nearly opposite where the marks on the pavement were, a door in the fence opposite to where they were standing.
Both he and Chick carefully examined this door and the fence for further marks without finding any.
Then Nick followed up the pavement, until he came opposite the door of the first house to be reached, and there beckoned to Chick, pointing with as much excitement as the great detective ever showed, to long red marks on the brickwork of the door.