'The Good Wife' spinoff cast news, plot spoilers: Sarah Steele's Marissa Gold is Diane Lockhart's secretary/investigator in spinoff

Sarah Steele, who recurred in 22 episodes of "The Good Wife" as Marissa Gold, has joined the upcoming as-yet-untitled spinoff coming to CBS All Access next year.

Marissa, a fan favorite character in the legal/political drama, was the daughter of Eli Gold (Alan Cumming). Eli was Peter Florrick's (Chris Noth) campaign strategist and crisis manager. Steele has signed on as a full-fledged series regular in the upcoming spinoff, TV Line reported. The actress is the first cast member to board the new series following its announcement earlier this year with Christine Baranski (Diane Lockhart) and Cush Jumbo (Lucca Quinn) attached. CBS announced the spinoff at its Upfront presentation in May.

Deadline said that Marissa will begin the spinoff as Diane's secretary before taking on the role of the lawyer's investigator.

Marissa was introduced in "The Good Wife" as Eli's daughter before she eventually played a key role in Alicia Florrick's (Juliana Margulies) life, particularly during her run for state attorney, in the drama's last few seasons.

Aside from her role in "The Good Wife," Steele is also known for appearing in the TV shows "Gossip Girl" and "Nurse Jackie."

According to Deadline, the 10-episode spinoff will find Diane and a young lawyer she mentors being forced out of Lockhart & Lee in the aftermath of a financial scam. The scam will reportedly ruin the younger lawyer's reputation and will wipe out Diane's savings. They will then be forced to join Lucca's firm in Chicago.

The upcoming spinoff will be produced and written by Michelle and Robert King, the creators of "The Good Wife."

The announcement of Steele's casting came just days after CBS All Access moved the premiere of "The Good Wife" spinoff to February 2017. The spinoff's premiere episode will air via a special broadcast on CBS before the series moves exclusively to CBS All Access.