Inclusion Criteria:
1. Body mass index of 17.5 to 38.0 kilograms per square meter (kg/m\^2), inclusive, and total body weight \>50 kg (110 pounds \[lb\]) at Screening.
2. Participants with a diagnosis of Parkinson's disease (PD) that is consistent with the United Kingdom (UK) Parkinson's Disease Society Brain Bank diagnostic criteria.
3. Must be modified Hoehn \& Yahr Stage I-III inclusive.
4. Must be on a stable dose of L-Dopa of at least 300 mg daily in conjunction with a dopa-decarboxylase inhibitor (e.g., L-Dopa/carbidopa, L Dopa/carbidopa/entacapone or L-Dopa/benserazide) administered at least 3 times per day for at least 2 weeks prior to the Day 1 Visit.
Exclusion Criteria:
1. Participants with a history or clinical features consistent with essential tremor, atypical or secondary parkinsonian syndrome (including, but not limited to, progressive supranuclear palsy, multiple system atrophy, cortico-basal degeneration, or drug-induced or poststroke parkinsonism).
2. Participants with a history of psychosis or hallucinations within the previous 12 months.
3. Participants with epilepsy, or history of epilepsy, or conditions that lower seizure threshold, seizures of any etiology (including substance or drug withdrawal), or who have increased risk of seizures as evidenced by history of electroencephalogram with epileptiform activity are excluded. Participants with a history of febrile seizures only are allowed with medical monitor approval.
4. History of substance or alcohol-use disorder (excluding nicotine; Diagnostic and Statistical Manual of Mental Disorders, 5th edition criteria) within 2 years prior to signing the informed consent form (ICF).
5. Participants who answer "Yes" on the C-SSRS Suicidal Ideation Item 4 (Active Suicidal Ideation with Some Intent to Act, Without Specific Plan) and whose most recent episode meeting criteria for this C-SSRS Item 4 occurred within the last 6 months, OR Participants who answer "Yes" on the C-SSRS Suicidal Ideation Item 5 (Active Suicidal Ideation with Specific Plan and Intent) and whose most recent episode meeting criteria for this C-SSRS Item 5 occurred within the last 6 months OR Participants who answer "Yes" on any of the 5 C-SSRS Suicidal Behavior Items (actual attempt, interrupted attempt, aborted attempt, preparatory acts, or behavior) and whose most recent episode meeting criteria for any of these 5 C-SSRS Suicidal Behavior Items occurred within the last 2 years, OR Participants who, in the opinion of the investigator, present a serious risk of suicide.
6. Participants who have attempted suicide in the past.
7. Positive result for human immunodeficiency virus (HIV) antibody, hepatitis B surface antigen, hepatitis B core antibody, or hepatitis C antibody with detectable viral ribonucleic acid (RNA) levels at Screening.
8. Have been diagnosed with symptomatic coronavirus disease (COVID-19) or test positive (i.e., using polymerase chain reaction \[PCR\] or rapid antigen test) for COVID-19 within 30 days prior to signing the ICF.
9. Participants taking strong or moderate cytochrome P450 family 3 subfamily A member 4 (CYP3A4) inducers or inhibitors or who would be likely to require concomitant therapy with CYP3A4 inducers or inhibitors during the trial.
NOTE: Other protocol-defined inclusion and exclusion criteria may apply.
