Linda Cardellini broke out at the turn of the millennium as the face of teenage angst in Judd Apatow’s “Freaks and Geeks,” a slice-of-life NBC series about high schoolers in suburban Michigan. A quarter-century later, she has returned to the Midwest to delve into a different phase of life as explored by a comedic auteur: the middle-aged malaise that forms the core of creator Steven Conrad’s HBO limited series, “DTF St. Louis,” or what ASL interpreter Floyd Smernitch (David Harbour) describes to his stepson Richard (Arlan Ruf) as “grown-up C’s.” Both Floyd and his new best friend Clark (Jason Bateman) are unhappy in their marriages and, by extension, their lives; the extreme measures the two men take to counteract that loneliness will end in Floyd’s death, the investigation of which drives the plot of the show.

“More than anything, it’s about intimacy, whether you do the things that they do in a relationship or not,” says Cardellini, who plays Floyd’s wife and Richard’s mother, Carol Love-Smernitch.

We’re speaking at a co-working space in Hollywood where the actor has just posed for a photo shoot, but she’s changed back into a casual outfit that feels more appropriate for unpacking the humble, low-key Carol, a white-collar worker at Purina’s corporate office who strikes up an affair with Clark over smoothies from Jamba Juice.