An investigation by Mediapart has revealed the chaotic management at the highest levels of the French state over the crucial issue of providing protective masks to help tackle the Covid-19 coronavirus pandemic. Our probe, which has analysed the situation since January and is based on numerous witness accounts and documentary evidence, highlights the hidden shortages, the unreliable health instructions, the neglected offers of help with importing masks, the continuing shortage of stocks and the way that some companies have been favoured. It also reveals the lies that have accompanied this mismanagement. Meanwhile hundreds of nurses have become infected with the virus. Yann Philippin, Antton Rouget and Marine Turchi report.