'The Good Wife' Season 5 Episode 12 Spoilers: Marilyn Investigates Voter Fraud [Video]

"The Good Wife" returned with Will taking on Alicia in court, again, and a surprise cameo that ended a paternity mystery. 

In "Goliath and David," Florrick/Agos goes up against Lockhart/Gardner in a case over musical copyrights. The case centers on a fictional "Glee"-esque show called "Drama Camp," in which the show used a musical group's cover of a rap song in both the show and on iTunes.

Will (Josh Charles) goes up against his former colleague and lover, Alicia (Julianna Margulies), in court, and tries to throw Alicia off her game. While she does get flustered, she proves that she has a reservoir of strength that allows her to continue fighting back.

Meanwhile, Diane (Christine Baranski) is trying to stop Will, who is emboldened by the success of the newly opened New York branch of the firm, from expanding to Los Angeles as well.

However, Diane is being outmaneuvered by Will, since he points out that she "walked away" from the firm, leaving him to take charge. 

Eli (Alan Cumming) sends Kalinda (Archie Panjabi) to find out who the father of Marilyn's (Melissa George) baby is to make sure the father isn't Peter (Chris Noth).

It turns out that the father is a very different Peter--Peter Bogdanovich, to be exact, the iconic movie writer, director, actor and producer, who makes a cameo in the episode. 

At episode's end, it is revealed that the surveillance footage of stuffed ballot boxes being carried into a polling place was obtained by a reporter, and the reporter is about to post it online. Now the hunt begins to find out leaked the video. 

On the next episode, "We, the Juries," "Alicia and Will each represent one-half of a couple accused of smuggling drugs, but chaos ensues when they insist on separate jury pools for their individual clients. Meanwhile, Cary tries to woo a Lockhart-Gardner client; Kalinda attempts to repair a damaged relationship; and Marilyn investigates possible voter fraud during the gubernatorial election."

Watch the promo below for "We, the Juries," which airs Sunday, Jan. 12 at 9 p.m. on CBS.