The introduction of roads in mountainous regions often induces instability, demanding site-specific knowledge for effective mitigation. This study examines a case of slope failure at Inarpani in Baglung along the Midhill Highway, revealing critical instability issues. Three Electrical Resistivity Tomography (ERT) profile surveys were conducted to uncover the lithology of the landslide area, followed by drilling of two boreholes for subsurface inspections and sample extraction for laboratory tests. Using the collected data, a GEOSTUDIO model was prepared for the critical section, with SEEP/W and SLOPE/W employed for slope analysis. The SLOPE/W analysis resulted in a very low factor of safety, on both the hillside (0.791) and valley side (0.799) of the road. The investigations and SEEP/W analysis identified the high groundwater table on the sand-dominant slope as the primary cause of failure. These findings highlight the need for effective water management to improve stability. Proper investigations and resolution of critical concerns in potential failure zones can significantly reduce roadside slope disasters in Nepal.