 In 1898 Hornung 's mother died , aged 72 and he dedicated his next book , a series of short stories titled Some Persons Unknown , to her memory . Later that year Hornung and his wife visited Italy for six months , staying in <unk> ; his account of the location appeared in an article of the May 1899 edition of Cornhill Magazine . The <unk> returned to London in early 1899 , to a house in Pitt Street , West Kensington , where they lived for the next six years . 
