Edgar Wallace 
Black Abbot [PDF ebook] 

They say the ghost of the Black Abbot has been seen near the old abbey, and Cartwright the grocer claims to have seen it too. Meanwhile Harry Alford, eighteenth Earl of Chelford is engaged to Leslie Gine, sister of Arthur, solicitor and gambler with the family fortune. The Earl had originally asked his secretary Mary Wenner to be his bride, but his half brother Richard intervened to stop the marriage. Plotting revenge, Mary proposes she and Arthur marry. Her dowry, she insists, will be fifteen tons of Spanish gold — the missing Chelford treasure.