Louise arrives in Albert Square in May 1998, just in time to halt the proceedings of her husband Terry's marriage to Irene Hills. Although their marriage had ended in separation many years ago, Terry is still legally married to Louise and had refused to grant her a divorce in order to get out of paying the settlement.
Louise had left both her children, in their teens, in the custody of their drunken and abusive father; she had subsequently had no contact with either. Both Tiffany and Simon find it difficult to cope with their mother's sudden reemergence, but Louise manages to win them round. After reuniting with her children, Louise decides to move to Walford, mainly to support Tiffany, who is going through a traumatic time after the break-up of her marriage to Grant Mitchell.
Louise seems to dislike Grant initially; she tries to convince Tiffany not to go back to him. Grant is desperate to save his marriage in order to remain close to his daughter, Courtney, and realising the influence Louise has, he makes a deliberate effort to woo Louise. Over subsequent meetings, it becomes evident that Grant and Louise are attracted to each other and Grant regularly makes advances on Louise. Louise initially denies her feelings, embarking on a fling with Gianni di Marco to put Grant off. However, on the night of her 40th birthday, the inevitable happens and Grant and Louise have sex. The next day, Louise is wracked with guilt, which is compounded by the fact that Tiffany has decided that she wants to reunite with Grant. In order to spare her daughter's feelings, Louise keeps the affair secret.
Louise is attacked in November of that year and it is Grant who comes to her rescue, which nearly leads to them having sex a second time, stopped only by Simon's unexpected appearance. Panicking, Grant declines to tell Tiffany about Louise's attack, fearing that Louise will be more likely to confess their affair in her emotional state. When Louise finds out that Grant has attempted to keep her daughter away from her, she goes round to The Queen Victoria public house to confront him, accusing him of using her for sex. However, a distraught Tiffany hears their entire conversation over the baby monitor.
Upon realising that her mother has betrayed her with her husband, Tiffany decides to flee Walford. Moments before she is about to depart, Grant accosts her and an argument culminates in Tiffany falling down the stairs and being hospitalised. After Tiffany recovers, she refuses to have anything more to do with Louise. After setting Grant up as the perpetrator of her accidental fall, she tries to leave Walford again but is run-over and killed by Frank Butcher on New Year's Eve 1998 before she can leave. On the day of her funeral, Tiffany's best friend, Bianca Jackson, discovers a letter from Tiffany explaining Louise's betrayal, upon which Bianca furiously threatens to tell Simon what Louise has been up to unless she leaves Walford. Louise flees in January 1999, leaving her son distraught.
Later that year, Louise returns following Simon's mental breakdown. Frightened that Bianca will get there first, Louise divulges her affair with Grant to Simon. This news only worsens Simon's mental state; he sets fire to his flat, causing himself burns. Simon decides to leave Walford soon after his recovery, and despite initial hostility, he and Louise part on good terms. After another trivial dalliance with Gianni and more squabbling with Terry, Louise decides to leave Walford too in April 1999.