Isabel Dalhousie thinks often of friends, sometimes of lovers, and on occasion of chocolate. As an Edinburgh philosopher, she is certain of where she stands. She can review a book called In Praise of Sin with panache and conviction, but real life is...well, perhaps a bit more challenging....

The person you are with is just like you: same background, same age, same interests. The perfect match. And it is an unmitigated disaster. Then, when and where you least expect it, you meet someone new. You seem to have nothing in common and yet, somehow, it feels totally right. Nick Hornby's brilliantly observed, tender but also brutally funny new novel gets to the heart of what it means to fall surprisingly and headlong in love with the best possible person - someone who is not just like you at all.

Unusual requests are commonplace at the No. 1 Ladies' Detective Agency, but so are very ordinary ones, such as a plea for money: when a distant cousin calls on Mma Ramotswe to ask for help with another relative's hip operation, tricky questions arise in regard to family responsibility. Mma Makutsi and Mr J. L. B Matekoni are far from convinced of the merits of the request, but it is hard for Mma Ramotswe, with a heart her size, to turn people away.

The story revolves around the comings and goings at No. 44 Scotland Street, a fictitious building in a real street in Edinburgh. Immediately recognisable are the Edinburgh chartered surveyor, stalwart of the Conservative Association, who dreams of membership of Scotland's most exclusive golf club. We have the pushy Stockbridge mother, and her prodigiously talented five-year-old son, who is making good progress with the saxophone and with his Italian.

Detective Ulf Varg from the Department of Sensitive Crimes is often called upon to investigate unusual matters. But rarely is he asked to conduct an inquiry on behalf of his own family. Is such a thing ethical? Adding to Ulf's moral discomfort is the fact that he does not exactly see eye to eye with his younger brother Bjorn - a leading player in one of Sweden's right-wing parties, the Moderate Extremists. Still, family is family, so Ulf finds himself working to uncover the mole leaking secrets to a rival party, the Extreme Moderates.