Alexander McCall Smith has given us more than two-dozen gentle, amusing, often whimsical and always thoughtful novels that take place in far-flung parts of the world. He first became famous for his bestselling novellas starring Precious Ramotswe in The No. 1 Ladies’ Detective Agency in Botswana. His books featuring Edinburgh philosopher Isabel Dalhousie have captured the imaginations of his readers and become bestsellers on their own.

Smith recently poked wry fun at himself in a National Public Radio appearance on “Prairie Home Companion” as an author in search of a muse. He was searching for language that would inject more action, guns, car chases --- some real excitement into his works. As he told Guy Noir, Garrison Keillor’s hard-boiled detective character, he appreciated the large following of “lady readers who enjoyed stories with tea and biscuits” but hopes never to have to insert the word “scone” into another novel. He wants to venture into the action-packed, hard-boiled world of readers who are the guys who drink beer and hunt bears, so he asked Guy for tips on writing action mysteries. Smith gets arrested for “writing while driving” and joyously finds himself “in the slammer” surrounded by Damon Runyonesque characters who keep him scribbling every cliché ever uttered in hard-boiled pulp fiction. He leaves jail a happy man, ready to tackle a new genre.

However, you won’t find a word of it in THE CHARMING QUIRKS OF OTHERS. What you will find is an Isabel Dalhousie rumination on the beiges and grays of human character, this time focusing on her being pressed into conducting an informal inquiry into the short list of candidates for headmaster of an exclusive boy’s school near Edinburgh. The current headmaster has accepted a post in Singapore, so the school is scurrying to find a suitable replacement. A member of the school’s board, a casual acquaintance of Isabel’s who has learned of her reputation for discretion, has come into possession of an anonymous note hinting of a scandalous event in one of the men’s past. The note does not indicate which man it is nor does it disclose the nature of the scandal. Isabel agrees to pursue it as far as she can with what little information she has. The plot thickens when one of the candidates turns out to be her niece Cat’s latest lover, of whom Isabel for once approves (Cat has a history of questionable taste in men), which of course places her on the horns of the dilemma of impartiality versus favoritism.

She discovers that one of the candidates has indeed encountered a tragedy in his past that may or may not point to a major character flaw. This discovery leads Isabel, and thus the reader, down the ethical briar path of what a reasonable person would do if they found someone in dire straits. Would he stop and help, or continue on because of the potential risk to his own life? And how would that decision affect the rest of his life? It’s one of the great charms of the Dalhousie books that they lead the reader to ponder their own concepts of right and wrong.

At home, Isabel encounters her own ethical conundrum with her young lover, Jamie, father of their two-year-old son Charlie. She discovers quite by chance that a seriously ill, beautiful young woman has come into Jamie’s life. Jamie has been secretive about this, leading to a potential threat of their relationship and planned marriage.

Tea and biscuits and sophisticated soliloquies on works of art, great writers and musical works are part and parcel of THE CHARMING QUIRKS OF OTHERS, another exquisite cozy from the philosophical mind of Alexander McCall Smith. One can only hope that he will leave the car chases and running gun battles to the Michael Connellys, Dennis Lehanes and Guy Noirs of the world.