Production on the final episode of "Friends" (search) is less than a month away - and already security plans are in place to keep the secret from leaking.

Taping of the episode - which is expected to be seen by as many as 40 million fans - will take place in front of a live audience at the end of January.

But the show won't air until May. Keeping the plot secret will be a major undertaking.

"There obviously will be precautions taken," a Warner Bros. spokesman said.

In the past, the producers of other popular TV series have filmed alternate endings in front of different audiences so that no one can tell whether they saw the actual finale.

Still, potential story lines for the final few episodes have already leaked onto the Internet.

A casting sheet was recently circulated to agents in Los Angeles and New York looking for an actor to play a real estate broker who would try to sell a house in the suburbs to Monica and Chandler, according to the Hollywood insider internet gossip sheet, filmjerk.com.

It also called for actors to play a pair of "50-something" neighbors who live in Westchester.

"Friends" officials say the story-line has since been dropped, but in many other cases denials have been part of a studio misinformation campaign to keep plots a secret.

Traditionally, when a show as popular as "Friends" goes off the air, producers go to great lengths to keep the plot of the final episode a secret.

When "Seinfeld" (search) signed off in 1998, NBC and producer Castle Rock Television beefed up security around the studio where the show was filmed and shot the final scenes of the episode without an audience to keep key details from leaking out before the May telecast.

Actors and crew involved in the episode had to sign confidentiality agreements regarding its content. And most of the cast weren't even given scripts as insurance that the story line would remain a secret.

What makes those plans more difficult is the short schedule, reportedly demanded by cast member Jennifer Aniston (search).

The only way NBC was able to get the entire cast to return for another season was to agree to film just 18 episodes instead of the usual 22 this year and wrap the show before February.

Typically, the season finale of "Friends" is filmed in March and airs in May.