She was created after the death of a previous replicant of Isobel and was given her memories.
Hythe brought Ash to Isobel at Ramanuja and the three searched for Cleo, with Isobel explaining to Ash that she was the previous Isobel replicant. After Ash determined Cleo's destination to be Arcadia and spotted Cleo in a crowd preparing to board a transport, Hythe held her at gunpoint and revealed the deception.
During a scuffle between Hythe and Padraic, Cleo's friend, Cleo spotted Isobel and embraced her. Hythe then killed Padraic and condemned Ash for her sympathy for replicants, and was promptly shot by Isobel. Isobel revealed to Ash that, despite being more loyal to her husband, possessed the memories of the previous Isobel and was thus an ally of Ash. Ash then left Cleo with Isobel to reach Arcadia.
However, the pair instead followed Ash in order to confront Alexander Selwyn back on Earth. Upon arriving at the Selwyn mansion in Santa Barbara, Cleo demanded of him to confirm that the reason he went after her was so that she could be given to Eldon Tyrell in order to be experimented upon. He confessed to this, but plead that they now could be a family again, prompting Cleo to hug him before going to the injured Ash. Isobel then went to him, killing him by breaking his neck. A Hythe replicant prepared to kill her before being stopped by another defective one, who requested the house and to be forgotten.
Isobel, Cleo, and Ash returned to the city, dining at a noodle bar. The mother and daughter confirmed their plans to go to Arcadia, offering to take Ash with them. However, the ex-Blade Runner declined, deciding that she belonged on Earth in order to assist fugitive Nexus-8s.