A new detector capable of measuring the LHC luminosity has been installed at the LHCb interaction point. It is named Probe for LUminosity MEasurement - PLUME. This detector is undergoing commissioning and will operate throughout LHC Run 3. It will enable real time monitoring of beam condition parameters such as luminosity, number of visible interactions per bunch crossing and LHC background. It will also cross-check the LHC filling scheme in real time, and contribute to the centrality determination for the LHCb fixed-target program. The detector is based on the detection of Cherenkov light produced in quartz material by charged particles moving upstream from the LHCb collision region. PLUME needs to provide both online and offline luminosity measurements with a time response that can be as fast as a fraction of a second, and it will ensure the vital luminosity-leveling procedure at LHCb and act as real-time alarm for LHC.