Beth Murphy is a realtor and the sister of twins Moira and Megan Murphy, who were also realtors. She was considered the "black sheep" among the trio, as her sisters didn't even trust her to show the houses. However, Megan had a bit more trust in Beth than Moira did, and she allowed Beth to help her out with their finances. Beth decided to embezzle from their profits to start her own business in an attempt to prove herself to her sisters, only to lose everything in the process. Megan found out about Beth's actions and confronted her, stating that Moira was right about Beth being a screw-up, leading to Beth bludgeoning Megan to death with a hammer in anger.
Beth covered up her murderous role and acted shocked to see Megan's body while presenting a house to a customer, with Moira being left to be accused of her sister's murder when she was at the scene. During Chloe and Lucifer's masquerade party, which was thrown to search for Megan's killer, Lucifer's transformation caused his aura to affect the guests, who voiced their desires to Lucifer. One of the masked guests was Beth, who stated that she wanted to get a flash drive that would reveal her actions, and it was afterwards that Chloe and Lucifer grabbed Beth and unmasked her. Beth confessed to the embezzlement and to Megan's murder, after which she was arrested.