The Transformers star is off and running during a workout in L.A. Plus: Ashlee Simpson-Wentz, Brad Pitt, Britney Spears and more

ON DUTY

Back to work on her hit drama, Mariska Hargitay finds a partner in crime-fighting in Wentworth Miller on the New York City set of Law & Order: SVU on Wednesday. The Prison Break hunk will guest star as a cop in the season premiere of the NBC show set to air Sept. 23.