The second-season opener of Without a Trace features an easy-to-solve crime and makes sure we bond once again with its central figure, Anthony LaPaglia's FBI agent Jack Malone. ''Trace'' commences as usual with its visual signature -- someone disappears, literally (and eerily) from the screen. But in a clever twist by series creator and writer Hank Steinberg, this time it's not a vanished person but an entire school bus. This ''Trace'' was less about the crime than quality time: quietly touching scenes of Jack taking his two daughters to school and a few subtle references (for the scads of new viewers ''Trace'' deservedly picked up over the summer) to the reverberations of last spring's season-ending hostage crisis in which Poppy Montgomery's agent Samantha Spade was wounded.
''Trace'' understands that people watch weekly dramas to become involved in characters' lives, yet exec producer Jerry Bruckheimer and Co. have caught on to the idea that although we'd like a few clues here and there -- something to connect us to the characters -- we don't want to know too much. The mysteries should extend to personalities as well as to how crimes have been committed. In this way, ''Without a Trace'' keeps us hooked by offering the unknowable, and the elusive promise of knowing all.