Anne Barker was Titus and Peri Delancey's nanny. In this capacity, she cared for their sons, Grahame and Zack. She changed her name from Abigail Spencer after being accused and acquitted of poisoning her rich father with nitroglycerin in 1991, when she was 15 and living in Michigan. During her trial, Sherlock Holmes corresponded with her as "Sean Holmes", helping to develop his deductive abilities.
|After Titus Delancey is found murdered by a nitroglycerin overdose, Holmes and Watson meet Anne at the Delancey's home. Holmes takes Watson outside and says that he knows the nanny. She was the prime suspect in the poisoning death of her father, but was acquitted and her name is Abigail Spencer. In "the box" at the 11th Precinct, Captain Gregson questions Barker who admits she was Abigail Spencer. She has no alibi but denies killing Titus. She changed her name and appearance to escape the media attention from her father's death, is angry that it will happen again and asks how they discovered her identity. Holmes says it was from her voice. Spencer is released and Holmes believes that she is being framed. Watson deduces that Holmes didn't recognize Spencer from her voice, but from a tattoo on her wrist. Impressed, Holmes relates that the poisoning of Abigail's father catalyzed his interest in detective work.
|Holmes was able to deduce that she did kill her father, an abusive man, but only after the trial was over and she was acquitted. Despite this, he still believes that the framer must have discovered her past. Holmes visits Spencer and reveals he is Sean Holmes. Beseiged by the media and fired as a nanny, she's still grateful to have Holmes to talk to. Later, Holmes shows her a video of her and Titus arguing. Professing she didn't kill him, Holmes provides details from their correspondence that proves she did kill her father. Angry, Spencer tells him to leave. ("Poison Pen")