He hired Toby to kidnap Jamie McCrimmon, but when Toby tried to get his pay, Arthur didn't remember hiring him. He later fought with Toby when Toby threatened to take the information he knew to someone who would pay for it. Toby knocked Arthur unconscious.
When Theodore Maxtible and Edward Waterfield found Toby's dead body, Arthur happened on the scene in time to prevent Maxtible from killing Waterfield. He disposed of the body. He angrily interrogated the maid Mollie Dawson when she said she had heard Victoria Waterfield's voice. The Second Doctor suspected something was odd about Arthur because he never ate or drank anything in front of other people. Arthur later got into a sword fight with Jamie but collapsed when the Daleks released their control of him. The Doctor then told Ruth to take him and Mollie as far away as possible. (TV: The Evil of the Daleks)