The Caves of Shend by David Hennessey — Read

It was no doubt a tangled skein that Dr Strong had taken in hand to unravel, but he had several powerful incentives to perseverance. He had only narrowly escaped with his own life, for the hand that bound him when unconscious would undoubtedly, but for Mrs Dalbert, have left him there to die.

Then, too, his growing love for Beatrice urged him to seriously attempt the solution of the mystery; and once set upon it, he found to his intense satisfaction that the mistress of 'The Towers' was as eager to obtain the solution of the mystery as himself, and that the pursuit brought him into very close and confidential intercourse with her.