In the movie, which marks Slattery's feature film directorial debut, a working-class married couple (Hoffman and Hendricks) face the untimely death of the wife's troubled son.
Hoffman saw the film (out on May 9) at Sundance. "He was very proud of it," Slattery told me Thursday at the L.A. premiere of the movie, hosted by Brooks Brothers and Sharper Image. "He was very pleased with it, which to me, means everything."
Hendricks said she was "extraordinarily grateful" for getting the chance to work with Hoffman.
"I flew into New York to have a rehearsal with him and John first," the Mad Men actress remembered. "I didn't know what to expect and found out very quickly that he was warm and collaborative and amazing and made you feel at ease. So that was a relief and then it was just pure sort of excitement after that."
The premiere was bittersweet. "This has been an evening of sort of talking about those memories and to celebrate him and present this to people who I hope enjoy seeing another performance from him," Hendricks said.
Hoffman died of a drug overdose on Feb. 2. He struggled with substance abuse in the past and sought treatment for a heroin relapse in May 2013.
The Oscar winner is survived by his longtime partner Mimi O'Donnell and their three children, daughters Tallulah and Willa and son Cooper.