The Fellowship of the Frog by Edgar Wallace

There was a concert that night at the Queen's Hall, and the spacious auditorium was crowded to hear the summer recital of a great violinist.

Dick Gordon, in the midst of an evening's work, remembered that he had reserved a seat. He felt fagged, baffled, inclined to hopelessness. A note from Lord Farmley had come to him, urging instant action to recover the lost commercial treaty. It was such a letter as a man, himself worried, would write without realizing that in so doing he was passing on his panic to those who it was very necessary should not be stampeded into precipitate action. It was a human letter, but not statesmanlike. Dick decided upon the concert.