Opal Town, a locale Mavis Clark has mined successfully before (and soon to be seen in a TV adaptation of this novel), is as convincingly drab as ever and rather more contemporary as the destination of two runaways--middle-class Sam and enigmatic Tony--who agree to work free for a down-and-out miner as an alternative to jail when they're caught in the act of stealing food from the town store. Sam, who narrates most of this, is primarily a follower, attracted to Tony's courage but suspicious about his role in another, unexplained petty theft and, later, paralyzed by the knowledge that Tony is wearing a stolen opal around his neck. Tony, whose behavior is a mixture of calculating self-preservation and passionate gestures, is less convincing on his own than as a foil for Sam's lack of commitment, and it is Tony's final rebellion, when he releases some penned camels before running away to avoid being sent to reform school, that gives Sam, destined for release to his family in any case, a chance to express his loyalty by taking the blame. At bottom, there's little to distinguish Sam from other confused teenagers, but Opal Town offers uncommon scope for both foolish mistakes and freewheeling dreams. . . and seen here, less encumbered by plot than it has been in previous visits, the lure is stronger than ever.