Matilda borrowed a diamond necklace from her wealthy friend to wear to a ball, but lost the expensive piece. Unable to find it, she and her husband worked for 10 years to pay off the 36,000 franc cost of an identical replacement necklace. One day, Matilda discovered from her friend that the original necklace was actually fake and only worth 500 francs, revealing how a small mistake ruined her life through years of hardship repaying a massive debt.