Several months later, Kat's grandmother Mo discovers that she is in prison for prostitution. Upon her release, Mo convinces her to return to Walford. Kat is determined to win Alfie back, but he is now in a relationship with Little Mo. Though he opts to reconcile with Kat, she is unwilling once she learns of his relationship with her sister. Kat rebuilds her relationship with Zoe, and they part on good terms when Zoe leaves to work as a holiday rep in Ibiza. Before Zoe leaves, Kat discovers that Zoe was involved in the murder of Den Watts (Leslie Grantham), and tells Kat that she had been lead to believe that she had killed Den until Sam Mitchell (Kim Medcalf) had told her the truth about Chrissie Watts (Tracy-Ann Oberman) being the murderer. Kat confronts Sam about letting Zoe believe that she had killed Den and threatens Chrissie to not let Zoe's involvement become known to the police. Chrissie agrees, but in return, asks for an alibi. Kat's cousin Stacey Slater (Lacey Turner) agrees to become Chrissie's alibi, but Chrissie is later caught out and arrested for Den's murder. When Nana Moon dies, Kat comforts Alfie and their feelings for one another once more become apparent. On Christmas Day 2005, they confess their love and depart Walford to travel across the United States.