The end is in sight for ABC's acclaimed island mystery "Lost," but fans will have to wait until 2010 for all the answers.

In a highly unusual move, the network announced plans yesterday to end the show after three more shortened seasons of 16 episodes each.

The episodes will air consecutively, repeat-free, from February to May.

ABC's step marks a response to the show's producers, who have been eager to set a finish line to better plot out their convoluted mystery of plane-crash survivors and to placate fans who are frustrated that the show seemed to be vamping its way to a conclusion.

"Among fans there was an unease that they were making an investment in a show that's complicated without any sense of where that's going to lead them," co-creator Damon Lindelof said in an exclusive interview. "From the very beginning, fans and even critics have been saying, 'Are you making it up as you go along?' " which was "a legitimate question."

Now, with a still far-away ending in sight, Lindelof says he and executive producer Carlton Cuse have "specific designs for ending the next two seasons" and promises that with the answer-filled season finale May 23, viewers "will begin to get an idea of what that design will be, and it will not be at all what they expect."

The finale completed filming in Hawai'i on Saturday.