Mystery and black humor set in a small Tuscan town

Summer's Lease, by John Mortimer. New York: Viking Penguin. 288 pp. $19.95. In his latest novel, John Mortimer whisks us off to a small Tuscan town full of expatriate Britons and natives skilled in exploitation. The Brits see the place as an outpost of Empire and spend their days searching for the necessities of life - Gentleman's Relish, the Daily Telegraph, steak and kidney pudding, and streaky bacon. Admirers of Evelyn Waugh, remembering that it was Mortimer who adapted that author's ``Brideshead Revisited'' for television, won't be surprised to find the self-absorbed community painted with Waugh-like black humor.

But there's mystery here as well as humor. In fact, mystery is piled so tantalizingly on mystery that we keep reading, even though his characters are rather unpleasant. It's hard to care about them, impossible not to care why strange things keep happening to them.

Molly Pargeter starts the whole thing off. Back in England, hungry for sun, Italy, and the paintings of the Masters, she answers an ad for ``villa to let near small Tuscan town, suit couple, early forties, with three children (females preferred).'' Why all this preciseness? And when she and her family get there, why does the water supply fail? Why are the neighbors so cagey about the landlord and his wife? Why is that corpse lying in the swimming pool? And so forth and so intriguing on and on. Puzzles like that kept me reading - I can even forgive Mortimer for leaving me with a pailful of red herrings at book's end.

In fact, who would be able to stop once they had read Mortimer's doom-laden opening sentence?

``The woman walked round the corner of the house and saw a snake consuming a large Tuscan toad.''

Pamela Marsh is a free-lance book reviewer.