A Study to Evaluate Cortisol Reserve in Response to Adrenocorticotropic Hormone (ACTH) Stimulation Test Following Baxdrostat Treatment Compared to Placebo in Participants With Uncontrolled Hypertension

Inclusion Criteria: * Participants with mean seated systolic blood pressure (SBP) on automated office blood pressure measurement (AOBPM) greater than equal to (\>=) 130 millimeter of mercury (mmHg) and less than (\<) 170 mmHg at screening. * Participants with mean seated SBP on AOBPM of \>=130 mmHg and \< 170 mmHg at randomization. * Participants must have a stable regimen of \>=1 antihypertensive medication (at least one should be a diuretic), for at least 4 weeks prior to screening. * Participants must have an estimated glomerular filtration rate (eGFR) \>=45 milliliter per minute (mL/min)/1.73-meter square (m\^²) at screening. * Participants must have a serum potassium+ (K+) level \>=3.5 and \< 5.0 millimole per liter (mmol/L) at screening. Exclusion Criteria: * Mean seated diastolic blood pressure (DBP) on AOBPM \>=110 mmHg at randomization. * Prior treatment (within the 4 weeks before screening) with angiotensin receptor Blocker (ARBs) and angiotensin converting enzyme inhibitor (ACEIs) (both taken simultaneously). * Serum sodium (Na+) level \< 135 millimole per liter (mmol/L) at screening, determined as per central laboratory. * New York heart association functional heart failure (HF) Class IV at screening. * Planned percutaneous coronary intervention/coronary artery bypass grafting or percutaneous coronary intervention/coronary artery bypass grafting done within 6 months prior to screening. * Uncontrolled diabetes with glycated haemoglobin (HbA1c) \> 10.0% (86 mmol/mol) at screening. * Fridericia's corrected QT (QTcF) value \> 470 milliseconds (ms) at screening, unless having a pacemaker. * Heart rate \< 45 or \> 110 beats/min in a resting position, as per vital signs assessment.