BOOK 15 IN THE MUCH-LOVED ISABEL DALHOUSIE SERIES

''You can''t go out of the house without tripping over a philosophical question.'' That is a remark made by Isabel Dalhousie to Jamie, the bassoonist who is her handsome younger husband. Isabel''s own life, of course, points to the truth of this observation: she seems to attract philosophical problems in much the same way as a magnet attracts iron filings.

In this latest movement in the symphony of her life, Isabel is faced with novel challenges, each of which tests her resolution to do the right thing. Dawn, a nurse in an infectious diseases ward, is let down by her lover and needs a place to live. Not surprisingly, Isabel offers her a roof over her head. What do you do, though if your house-guest locks herself away and avoids all contact?

And then there is the pompous and slippery Professor Robert Lettuce. He is planning a prestigious conference, and involves Isabel in it. But look at the budget: why is there such a large payment for Lettuce himself and for a young female assistant? Isabel is suspicious.

Other intriguing problems abound, including Isabel''s involvement in a book group threatened by discord and bickering. Isabel remains calm. Of course she does. She knows the power of love, reason, and a clear head to resolve all of these issues, and more.

PRAISE FOR THE ISABEL DALHOUSIE NOVELS:

''Isabel Dalhousie''s charm is undeniable'' Sunday Times

''The No. 2 Lady Detective . . . anyone who loves Precious cannot fail to be charmed'' Mail on Sunday

''Delightful . . . McCall Smith is a writer who celebrates kindness, in short supply in the world today'' Sunday Telegraph

''McCall Smith''s greatest gift as a writer - and God knows this is just one of many - is that he can write likeable characters'' New Statesman