S1:E10
Nana Gallagher Had An Affair
Original Air Date: Mar 13, 2011
Monica's return wreaks havoc on the Gallagher clan, leaving the children determined to find out if Frank is their real father; disgusted with Monica, Fiona moves in with Steve next door; Karen accepts Eddie's invitation to a Purity ball; Frank hits a new low when he uses Carl to stop a disability worker from tampering with his free money from the state.