Ready or Not’s” Adam Brody has signed on to star in “The Kid Detective.”

Sophie Nelisse will co-star in the dramedy from writer-director Evan Morgan.

Brody will star as a once-celebrated kid detective, now 31, who continues to solve the same trivial mysteries between hangovers and bouts of self-pity until a 16-year-old client (Nelisse) brings him his first “adult” case: to find out who brutally murdered her boyfriend.

William Woods and Jonathan Bronfman will produce, while Brody, Jeff Sackman, Berry Meyerowitz, Mark Gingras, John Laing, and Gareth Morgan will executive produce. Aqute Media is handling international sales with Level Film distributing in Canada. Production will start in late September.

Brody’s most recent appearance is in Fox Searchlight’s horror pic “Ready or Not” starring Samara Weaving, which hit theaters Wednesday and has earned strong reviews. The former “O.C.” star is about to begin production on FX’s limited series “Miss America,” which stars Cate Blanchett, and is also known for his role in Karyn Kusama’s cult favorite “Jennifer’s Body.”

He is represented by UTA.

Nelisse, who is represented by ICM Partners, appeared in “47 Meters Down: Uncaged” and also starred in 2013’s “The Book Thief” and 2015’s “The Great Gilly Hopkins.”