An Inspector in Scotland Yard living in the UK. She worked closely with Dr. Ian Wexler. Being described as the "British version of Seeley Booth" while Ian was the "British version of Dr. Brennan". Cate and Ian were somewhat antagonistic and argumentative towards each other but remaining close friends and on-off sexual partners. Cate reveals she has many on-off sexual partners, but Ian was one of the best, Brennan described Cate as being a woman with a "strong sexual appetite" who was unfazed by negative moral opinions of that.
She attended Booth's lecture at Scotland Yard and claims to have enjoyed it greatly. She works with Booth and Brennan to solve the murder of Portia Frampton, managing to secure a gun for Booth despite English laws on gun control. She and Booth appear affectionate, with him giving her the nickname "Pritch".
In the next episode, Ian Wexler dies and Cate requires Brennan to identify to body. It is confirmed to be Ian and that he was in fact murdered. Cate is deeply saddened by the death; she breaks down in tears while informing Wexler's students about his death. She said Ian had a look when things got worse and is reminded of it when looking at Brennan which again upsets her.
She leads the investigation into Ian's death, however once her sexual relationship with Ian came to light - which she kept secret to avoid being taken off the case - Brennan and Bones have a hard time trusting her. She was adamant that she wasn't jealous of Ian sleeping with other women since the practice made him better in bed. She helped Brennan and Booth catch Ian's murderer and she was there to arrest her.
Cate believed Brennan had slept with Ian and was surprised to find out she was wrong. She subtly implied Brennan should try sleeping with Booth. She bid farewell to Booth and Brennan and pretended to knight Booth. She considered it an honor to work with them both and offered Booth a lift to the airport (something Cam did with Grayson before she slept with him in the last episode) however Booth explains he's travelling with Brennan and they decide to leave before someone else gets murdered. He told her to visit him if she was ever in the colonies.