Miranda Richardson and Rachael Leigh Cook have joined WB’s gangster thriller, “Get Carter” starring Sylvester Stallone.

Stephen Kay (“The Last Time I Committed Suicide”) will direct the remake of the 1971 pic about a revenge-bent mobster (Stallone) scouring the underworld after his brother’s murder. Marc Canton, Neil Canton and Elie Samaha serve as producers.

Richardson will play the female lead, the widow of the slain brother. Cook will play their daughter.

Richardson’s previous film credits include 1997’s “The Apostle” and 1996’s “The Evening Star.” Cook recently appeared in Miramax’s high school make-over comedy “She’s All That” and New Line’s “Living Out Loud.”

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Aussie actress Radha Mitchell (“High Art”) is joining the indie love story, “Cowboys and Angels” for director Gregory Haynes (“Heaven or Vegas”). Greggory Peck and Kathryn Arnold (“The Velocity of Gary”) produce under the Smokin’ Dawgs banner.

“Cowboy” co-stars include Adam Trese (“Polish Wedding”) and Mia Kirshner (“Mad City”).

Mitchell will begin work on writer-director David Seltzer’s “Anasazi Moon” opposite Gary Oldman and Skeet Ulrich next month. She will next appear in USA Films’ February 2000 release, the sci-fi thriller “Pitch Black” alongside Vin Diesel and Cole Hauser.

The actress is repped by ICM and manager Rick Ax.

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Joseph Lawrence has signed on to the sequel “Urban Legend 2” for Phoenix Pictures. Neal Moritz will again serve as producer, along with Gina Matthews and Richard Rothchild. Brad Luff and Nicholas Osborne exec produce and Christy Prunier and Nick Morton will oversee on behalf of Phoenix.

Tyro helmer John Ottman directs the campus-set thriller. Lensing will begin next month in Toronto. “Urban Legend” starred Rebecca Gayheart, Alicia Witt and Jared Leto.

Lawrence has practically grown up onscreen, with roles on such long-running series as NBC’s “Blossom” and “Brotherly Love.” Once known as Joey, he has such film credits as 1985’s “Summer Rental” and the recent indie “Tequila Body Shots.” He is repped by manager Chuck Binder and the William Morris Agency.

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Martha Plimpton has signed to a multi-episode role on NBC’s “ER” as a waitress who works in a nearby eatery.

The hospital drama has signed numerous actors to do surgical stints in an effort to maintain its toehold as primetime’s powerhouse. Thesps who will appear this season include Rebecca DeMornay, Maura Tierney and Alan Alda.

Plimpton has extensive screen credits, most recently appearing in Par’s “200 Cigarettes.” Others include “I Shot Andy Warhol,” “Parenthood” and “The Mosquito Coast.” She is repped by Alan Somers of Somers Teitelbaum David.