Landslides give almost no warning, and this episode of the Deadly Disasters series builds its case around three that turned catastrophic. In California, months of drought and wildfire strip hillsides bare before a heavy rainstorm sends walls of mud through neighborhoods below. In Venezuela, a chain of landslips along the coast erases roughly 100 kilometers of shoreline in a single event. The most harrowing segment revisits Aberfan, the Welsh mining village where a coal-tip collapse buried a primary school full of children, a disaster that reshaped British safety regulation. Survivors describe the sound and speed of the mud arriving, while geologists and disaster researchers explain the mechanics behind each collapse, from saturated slopes to unstable spoil heaps. The film moves between archival news footage, present-day interviews, and expert diagrams to show why these slides happened, why they could not be stopped once triggered, and what each community learned, or failed to learn, about the ground beneath it.