A Song in Stone — Walter H. Hunt

There is a mystery in a chapel, and a man who must find the answer.

A Song in Stone begins with the premise that Rosslyn Chapel in Scotland is part of an unfinished larger church - and that it contains a mystery, one clue of which is found in the intricate stonework of the chapel. It goes from there to the Middle Ages, taking Ian Graham, currently-unemployed television personality, with it, literally, as he tries to learn the chapel's secret before it is too late to return to his own time, his own life.

Before he goes, he must find the music that the stone points to.