The purpose of this study is to examine the effects of a drug called RO7486967 in people with Parkinson’s disease. Researchers want to learn what happens to RO7486967 once it is inside the body; they will compare the effects of RO7486967 versus placebo (inactive substance) on inflammation in the brain and Parkinson’s disease symptoms. Some evidence suggests that people with Parkinson’s disease may have more inflammation in the brain. A key part of this inflammation is a protein called NLRP3. RO748967 blocks NLRP3, which might lower the inflammation in the brain. Study procedures include blood draws, ECGs (electrocardiograms), imaging, lumbar (spinal) puncture, questionnaires, and medication administration. Participants will be required to travel (covered by the sponsor) to an outside imaging facility in Connecticut. Length of treatment is 28 days; the length of participation is approximately 102 days (which includes a 60 day screening window and a 14-day follow-up).