Thirteen eerie yet oddly cheery stories from the ever-reliable Aiken--mostly set in Cornwall (her favorite locale), mostly contemporary, and mostly ghostly. In "Lob's Girl," a German shepherd is so attached to teenager Sandy Pengelly that he walks 400 miles to stay by her side. . .and comes back from the dead to save her life. Similarly, in "Miss Spitfire," an old, dying RAF vet is reunited with his long-dead True Love--who makes a ghostly reappearance just in time to foil a dastardly hijacking. And the other spooks here include a chattery Scotswoman (haunting the house where she was murdered), vengeful spirits within the pavement of a road, and a hunchback who was cheated of his rightful romance. Somewhat less effective are Aiken's ventures into other occult formulas: the lethal power of an evil talisman, stolen from a museum during a school outing; the sudden death of a boy's least favorite teacher--caused, perhaps, by his vivid dream-powers. But one of the standouts here is a completely non-supernatural thriller: "The Windowbox Waltz," which saucily packs enough plot for a Buchan novel--teenager Rosemary gets entangled with spies--into 20 pages. And the collection's closer is a brief, darkly amusing daub of doomsday science-fiction: an English-garden encounter between a teenage alien and an elderly minister. True, Aiken's teen-age heroes and narrators can occasionally be too bland or sweet. ("So, our hearts going pit-a-pat. . .") For the most part, however, these are crisp, unfussy mini-chillers--tidily plotted, reasonably varied, nicely balanced between creepiness and warm sentiment.