Peter MacNicol and Kelli Williams aren't lawyers, but they're not strangers to playing them on TV. The David E. Kelley veterans will return to the courtroom on NBC's legal soap opera "The Lyon's Den."

MacNicol will play Darrell Nix, a genius computer mogul. Battling schizophrenia, he enlists Jack Turner (Rob Lowe) to help him maintain control of his company. Opposing Turner in the Nix case will be Monica Crane (Williams), a corporate lawyer who will be a worthy adversary. While MacNicol is only slated for one episode, Williams is signed for two further appearances.

In 2001, MacNicol won an Emmy for his performance as John "The Biscuit" Cage on Kelley's "Ally McBeal" (he was nominated two other times). He previous worked with Kelley as a regular on "Chicago Hope." His film credits include "Ghostbusters 2," "Baby Geniuses" and "Sophie's Choice."

Williams left Kelley's "The Practice" as part of the major cast purge that preceded this season. She has made appearances on "Scrubs," "Sisters" and on Kelley's "Picket Fences."

The episode of "The Lyon's Den" featuring the two actors will air later this fall. For the season, the Sunday night drama is averaging just over 10 million viewers per episode.