This study examines the critical impact of continuous rainfall on the stability of the Malin slope, which experienced a catastrophic landslide in July 2014. To understand the relevant physics that initiated landslide, seepage and back analysis of the unsaturated slope were performed. The results show that antecedent rainfall played a role in slope instability. Change in volumetric water content and pore water pressure also have a big impact on slope instability. The study provides a comprehensive analysis of the infiltration within the soil. The findings reveal significant moisture accumulation and rising pore pressures due to sustained rainfall, which progressively weakened the slope’s stability. The Factor of Safety (FoS) decreased from 1.36 to 0.976, indicating failure. This research underscores the importance of integrating slope stability analysis with transient seepage monitoring to predict and mitigate rainfall-induced geotechnical hazards.