When Carol discovers that Lillian slept with her husband, Brendan, years previously, she reports her for benefit fraud, and benefit officers swarm the estate. This causes a public outcry as half of Chatsworth are claiming. Frank impersonates Lillian's husband in order to protect his benefits, which upsets Sheila. Can Frank win her back by making the big commitment: marriage? Meanwhile, Carl falls for Lip's latest girlfriend, Emily, and poses as her brother in order to fool Social Services. However, his paranoia goes into overdrive when he becomes convinced Lip and Mandy are having an affair, leading to a confrontation between them and an angry stepfather with a baseball bat. Elsewhere, Tony is having trouble with women, so Sheila steps in to help him.

The Gallaghers are pleased when Carl starts bringing money into the household, but Lip is horrified to discover his brother's mini-enterprise is dealing drugs for the Maguires, and when someone informs the police and Mandy finds herself behind bars, Mimi and her son Shane Maguire (Nicky Evans) launch a manhunt for Carl. It falls on Lip and Ian to uncover the real traitor, save their brother from a savage beating, and save Mandy from a prison stretch. Will Lip and Mandy finally confront their feelings for each other before it's too late? Meanwhile, Sheila becomes convinced Karen is a lesbian and invites her and Jez (Lindsey Dawson) to dinner, so Frank decides to play Karen at her own games.