This is a randomized (study medication assigned to participants by chance), double-blind (neither physician nor participant knows assigned study treatment), placebo-controlled (participants are randomly assigned to a test treatment or to an identical-appearing treatment that does not contain the test drug), and multicenter (when more than one hospital or medical school team works on a medical research study), study of esketamine in participants with major depressive disorder (MDD) in participants who will be assessed to be at imminent risk for suicide, as measured by the change from Baseline on the Montgomery-Asberg Depression Rating Scale (MADRS) total score at 4 hours postdose on Day 1. The duration of study will be approximately 81 days per participant. The study consists of 3 parts: Screening (that is, with in 1 day before study commences on Day 1) and double-blind Treatment (from Day 1-25) and Follow-up (from Day 26 up to Day 81). All the eligible participants will be provided standard care treatment and will be randomly assigned to either esketmaine or placebo treatment. Esketamine/placebo will be administered by intranasal route (delivery of medications through the nasal mucosa) two times per week for 4 weeks. Efficacy of the participants will be primarily evaluated through MADRS. Participants' safety will be monitored throughout the study.