After being released from prison for assaulting a teenage boy who propositioned Whitney Dean, Tony joins his partner Bianca Butcher and her family in Walford, including her son Morgan Jackson-King, whom he has adopted. It is revealed that he is a paedophile who has been grooming and sexually abusing Whitney, Bianca's adopted daughter, since she was 12. He immediately resumes his sexual relationship with Whitney, despite his displeasure at her more adult appearance, insisting she remove her make-up and jewellery. When Whitney gets a role in the school play, Romeo and Juliet, Tony is angry about having less time with her, becoming jealous of her co-star Peter Beale. Tony deceives Whitney into believing they will run away and start a new life together when she turns sixteen. Whitney gives him money she has been keeping for his return, which he gives Bianca as a deposit for a flat. Tony assaults Peter as a result of his growing jealousy, and is nearly reported to the police by Peter's sister Lucy Beale. Whitney convinces Lucy not to go to the police, but not before Lucy tells Bianca what happened. When Bianca angrily tells Tony that she is not a child anymore, he realizes he is no longer attracted to her.
Tony begins grooming fourteen-year-old Lauren Branning, supporting her when her mother Tanya Branning is arrested for the attempted murder of her father. He plans to take her to a concert, but Lauren's father Max Branning uncovers her hidden clothes and refuses her permission to attend. When Whitney's sixteenth birthday arrives, she books flights so they can run away together. Attempting to foil her plan, Tony steals her passport but it is found and returned. On her birthday, Whitney tells Bianca about her relationship with Tony, believing that they are going to leave together. Horrified, Bianca calls the police, and Tony is arrested. He is later released on bail and visits their home in an attempt to convince Whitney not to give a statement to the police. He is attacked by Bianca's ex-husband Ricky Butcher and re-arrested for breaking his bail conditions.
Before his trial, Tony attempts suicide. Whitney tries to visit but is refused, and Bianca sees it as a form of manipulation. Tony repeatedly attempts to contact Whitney by phone, but after the first day of the trial, he flushes the SIM card down the toilet in his cell. When Whitney's brother Ryan Malloy tries to attack Tony in court, Whitney says she will refuse to testify, claiming her witness statement was a lie and she was forced to say it. Bianca explains to Whitney that Tony will be set free and that he will target other children. Tony's barrister, Mrs Taylor, cross-examines Whitney, trying to imply that she pursued him for several years, saying she refused to take 'no' for an answer and lied about the accusations. Tony shouts out that he is innocent but Whitney says she trusted him and he abused her, revealing the truth about the relationship. After leaving the courtroom, Whitney gives her barrister, Vivien Easley QC, a mobile phone with messages from Tony on it. A week later Tony is found guilty of all charges and sentenced to 13 years in custody. He smirks as the verdict is being read out but is taken away with his head in his hands.
Over three years later, Whitney receives a note from Tony via one of his former prison friends, saying that he always loved her. Whitney attempts to visit Tony in prison, but she is told that he killed himself in his cell.