Roxy is determined to win Kevin back and attempts to manipulate him by claiming she had his child, knowing that he and Veronica have been struggling with fertility.
This episode centers on Kevin Ball and the sudden re-emergence of a complicated past relationship. [S3E5] Old Flame
If you were referring to a different popular show where the fifth episode of Season 3 has a major plot point involving an "old flame" or similar drama, it might be one of these: Roxy is determined to win Kevin back and
Meanwhile, Carol seeks revenge on Lillian for an old affair by reporting her as a benefit cheat, and Carl finds himself in a messy love triangle involving Lip. Other Notable S3E5 Recaps [S3E5] Old Flame