Lewis Grantley is English but has spent most of his life abroad. Now twenty-five he spent the past eight years with a rich gentleman, Sir Patrick Murray, who informally adopted him after his parents died. Lewis truly loved the old man and had no idea he was his heir. Now he has no sooner got over the shock of Sir Patrick's death, and of becoming a rich man, than he learns that Sir Patrick had three heirs who were bypassed in Lewis's favour.
After a little time has passed, Lewis decides to travel incognito to his estate in Scotland and see what he can learn about the bypassed heirs. He has a quixotic idea of marrying one of the three ladies as a way of keeping the estate in the family. To his surprise he sees that the two eldest sisters, Margaret and Jean, are "old" - being 40 and 38 respectively; and that the other sister Lilias (always in a blue veil) is kept in the background - perhaps she is an invalid. But he likes Miss Jean as he gets to know her, and seriously considers going forward with a proposal.
Of course Lilias is in fact a lovely young woman; and the ensuing comedy of errors seems to offer no way "out" again for the honourable Lewis.
Biographical and other notes
The fictional Murkley Castle and "the old Castle" were based on New Murthly Castle and [old] Murthly Castle in the Perthshire Highlands. Sadly New Murthly Castle was demolished sometime between 1948-1950.
Fyi, for several years painter John Everett Millais and his wife Effie spent each Autumn at Birnam Hall in the grounds of Murthly Castle. His painting of the old castle is above.
The book's title is from a song in Shakespeare's As You Like It.