Lost is back with new episodes Thursday, and I couldn't be happier.

Well, I could be a little happier. Lost so loves mystery and surprise, it's difficult to talk about it without giving something away.

Indeed, when ABC sent out a disc with the first two episodes of the fourth season, it asked ''that you use discretion in reviewing this show by not revealing any plot details that contain spoilers.''

And the network went on to list five different plot points it did not want given away.

But over its first three seasons, including its often frustrating third, Lost became so entangled in enigmas that some viewers simply gave up trying to keep track. After building a relationship between viewers and characters from the first couple of seasons, the show pushed many of them aside in order to focus on new people, the ever-expanding band known as the Others.

ABC has taken steps to bring viewers old and new back into the mix. Tonight it will replay the third season's two-part finale (already available on DVD) in an ''enhanced version.'' According to the network, that will include on-screen text about clues in the show and background information for new viewers. Thursday, it will precede the new episode at 9 p.m. with an 8 p.m. telecast called Lost: Past, Present & Future, recapping the show for newcomers but in a way the network claims ''current viewers will also find illuminating.''

All of which adds up to ABC saying: Please come back! Please! It'll Be Better! Honest!

And it is.

Without getting into those five secret things, Lost gets off to a thrilling start, generating new questions, but doing so in a way that begins to fill in the gaps left from previous seasons.

At the end of the third season, the show made several sizable revelations. First, at least some of the survivors from the crash of Oceanic Air Flight 815 did indeed get off the mysterious island that was the setting for most of Lost. But their seeming rescue had not led to happy endings. Indeed, at the end of the third season, Jack (Matthew Fox) was longing to go back to the island, to make amends for some error along the way.

At the same time, the people who appeared to have come to the survivors' rescue were not necessarily what they seemed. In one of the best moments Lost ever had, a drowning Charlie (Dominic Monahan) used his final moments to scribble on his hand a three-word warning that the rescue ship wasn't what they thought.

Charlie's warning is pivotal in the fourth-season premiere, as castaways must decide whether to believe in the possibility of rescue or to not believe, even fear it.

That's not a spoiler. Promotional spots for the series have already suggested an island with people divided. Indeed, a great deal of the series has been about different approaches to belief, as embodied by Locke (Terry O'Quinn) and Jack. That schism reached a peak at the end of the third season, with a violent result, and it carries over into the fourth.

That being said, a major sign of the show's new wooing of viewers is the way that Hugo ''Hurley'' Reyes (Jorge Garcia) is a key player in the decisions everyone must face. Hurley has long been an audience favorite, probably the most likable character of all the castaways. And, with his common-sense approach to almost everything, he is the viewers' surrogate in Lost's weird world.

But it's not all about Hurley. There are eerie forces at work, some old and at least one new. Ben (Michael Emerson), the leader of the Others, has not gone away. It's still not clear how destiny plays a role as we get glimpses of people's lives off the island.

Still, the questions don't feel as burdensome as they did leading up to the end of the third season. People are on the move. Shocks big and little lead into commercial breaks. There is plenty for Lost fans to discuss, and to relish.