In this talk, we'll explore a transformative journey at a Barcelona Water Management company, tasked with tripling development speed for a new software system being built by a team of 70 individuals. As an Agile Coach, I introduced Large-Scale Scrum (LeSS) to steer the project, beginning with innovative team self-selection and a weeklong Inception workshop for business and technical alignment, estimation and roadmap planning. Despite early efforts, we faced a stark reality: the ambitious timeline was unattainable, leading to the project's premature conclusion. This outcome, while initially seen as a setback, underscored LeSS's value in early failure detection—shifting from a potential multi-year misadventure to a crucial learning phase within a couple of months. Key takeaways include the critical role of technical seniority and proper product ownership, the power of providing transparency and fostering adaptability, and the strategic agility LeSS provides, offering invaluable lessons for scaling agile practices effectively.