'The Middle' Sneak Peek: Molly Shannon Returns!

Frankie's type-A sister Janet is back, and her "help" is doing more harm than good.
Tonight, Molly Shannon reprises her role as Patricia Heaton's sister, volunteering to help run the Heck household while Frankie crams for her dental school finals.
Check out a sneak peek of the hilarious episode in the video above!
The Middle airs Wednesdays at 8 p.m. on ABC.