Will Packer Productions has teamed with Focus Features to develop a female-driven thriller “When I Was You,” Variety has learned exclusively.

Based on a novel by Amber Garza, “When I Was You” centers on a woman named Kelly Medina who becomes obsessed with another Kelly Medina — a single mother half her age who lives in her same town, has a baby boy, and has her whole life ahead of her. When they become friends, she finds a renewed sense of purpose taking care of the young woman and her baby.

“Amber Garza writes edgy and tense psychological thrillers that keep her readers on the edge of their seats,” Packer said. “We’re excited about collaborating with Focus Features on material this good.”

Garza has also authored “The Girl Frozen in Time,” “The Last Time I Saw Her,” and the “Prowl” trilogy.

Production, casting and further plot details on “When I Was You” have yet to be announced.

Will Packer and James Lopez will produce the movie under Will Packer Productions. The studio’s feature films have earned more than $1 billion from a slate that includes “Girls Trip,” “Night School,” “What Men Want,” “Little,” and “Think Like a Man.”

Focus Features and Will Packer Productions will also develop an ensemble film set in and around the Wattstax music festival in 1972 at the Los Angeles Memorial Coliseum. Wattstax was a benefit concert that commemorated the deadly 1965 riots in Watts in a predominantly African-American neighborhood in Los Angeles.

Focus Features debuted “Harriet,” “Downton Abbey” and “Dark Waters” in theaters this year. Upcoming releases for the specialty studio include “Emma” starring Anya Taylor-Joy and Johnny Flynn, “Let Him Go” with Kevin Costner and Diane Lane and Jon Stewart’s “Irresistible” starring Steve Carell, Rose Byrne, and Chris Cooper.

CAA represented the book on behalf of The Gernert Company. Mira will publish the novel, with an anticipated release in August, 2020.