As part of the launch effort for its new legal drama “Conviction,” NBC is offering the premiere episode on the iTunes Web site for free before it airs on broadcast television. Viewers will be able to download the episode beginning Feb. 21, more than a week before the series’ debut Friday, March 3.

Beginning March 4, episodes will be available for purchase and download for $1.99 the day after airing.

“The multiplatform efforts are a buzz generator for certain shows such as ‘Conviction,’ and we want to proactively reach out to these viewers who have many options for entertainment,” Jeff Zucker, CEO of NBC Entertainment Group, said in a release.

NBC will tag a portion of its show promos with an on-screen graphic promoting the free preview. It will also be promoted online on iTunes and across NBC Universal’s Web properties.

“Conviction,” which follows the lives of young prosecutors in New York, is a Wolf Films production in association with NBC Universal Television Studio. Dick Wolf, Walon Green, Rick Eid and Peter Jankowski are executive producing.