The Lady in Blue by Fred M. White

The beckoning forefinger was not to be ignored.

Just for a little time Kelso had entirely forgotten the strangeness of his surroundings, and the possible danger which might lurk in this gloomy and mysterious old house. It had been enough for him that Audrey was found, and that, so far, all the acute anxiety as to her welfare was at an end. But there would be a long way to go, and many obstacles to smooth away, before the path to happiness was cleared again. For there were strange secrets here, and, perhaps, even the shadow of crime. Later on, he might induce Audrey to tell him everything, but there was no time to think of that now.