Bipolar disorder is a severe chronic mood disorder that affects up to 4% of the adult population in the United States. This study will assess how safe and effective ABBV-932 is in treating participants with bipolar I or II disorder. ABBV-932 is an investigational drug being developed for the treatment of depressive episodes in adult participants with bipolar I or II disorder. Study doctors put participants in 1 of 4 groups, called treatment arms. There is a 1 in 4 chance that a participant will be assigned to placebo. Around 160 adult participants with bipolar I or II disorder will be enrolled in approximately 40 sites worldwide. Participants will receive oral capsules of ABBV-932 or matching placebo once daily for 6 weeks. The treatment period will be followed by a safety follow-up (SFU) period for 4 weeks. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular weekly visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.