A second juggling act, and quite an unbalanced one, for Cambridge inquiry agent Laura Principal (Every Breath You Take, 1994). With one hand, she's supposed to solve the mystery of the missing properties at rehearsals for Thomas Butler's new West End play, and with the other, she's to figure out who entered Marcia Shields's house with a key and left with several uninsured paintings. Life gets even more complicated when the first of these cases boomerangs, as the Filipina servant Laura spoke to at Butler's house disappears, along with any acknowledgment by Butler's family that she ever existed. Though Butler wastes no time in pulling Laura off the theater robberies (a disappointing loose end), she's determined to track down Marilou Flores, the missing Butler maid--and then, after the Kensington police find Marilou fatally bashed and trashed, to track down her killer. Treading perilously near the same trails as Ruth Rendell's nonpareil Simisola (1995), Laura discovers the same brutal truths about the ways ``British immigration rules provide structural support for slavery.'' But there's nowhere near as much at stake in the Shields robberies, whose solution Spring saves for last. One case is clever, then, the other deeply felt, though Spring, unlike Rendell, never does manage to meld both kinds of interest together.