Critic's corner

* "Who is this guy?"

That's the question posed in a terrific episode of Lost (ABC, tonight, 8 ET/PT) that also answers a far more pressing viewer question: Can this promising new series produce a regular episode that's as gripping and entertaining as the pilot? And the answer, I'm thrilled to say, is "yes."

Written by Angel 's David Fury, tonight's cleverly structured hour focuses on the mysterious Locke, played with his signature blend of charm and menace by Terry O'Quinn. While Locke takes charge of a boar hunt, flashbacks unveil a string of increasingly surprising secrets. The final twist is a shock, but it's not a cheat. The clues are all there, if ...