Not a Great Bet is the seventh episode of Season 4 and the 43rd overall episode.
Gretchen goes home for the birth of her brother's baby, but instead ends up reconnecting with a friend from her past who inadvertently reveals why Jimmy may have left her.
The episode follows Gretchen as she goes to her parents' home for the birth of her brother's first child.
She discovers that her 8th grade friend Heidi (Zosia Mamet) survived leukemia and now owns their old roller rink hangout.
Avoiding her familial duties, she reconnects with Heidi. Heidi does not share her enthusiasm, but they both go an old derelict mall to drink and smoke.
They find some stressed out teenagers just hanging out and try to get them to loosen up.
The police raid the mall and they escape in Gretchen's rented pickup, abandoning it in a corn field. As they walk home,
Gretchen says she wants to stay in town with Heidi, but Heidi says they were never friends after middle school as Gretchen was so unstable. Gretchen yells abuse at Heidi as she walks away.
Gretchen finally arrives at the hospital, peeks in at her family with the new baby, and leaves.