The LHCb Upgrade II will take full advantage of the capabilities of the High Luminosity LHC to search for new phenomena in flavour physics and is foreseen to take data after the long shutdown 4 of the LHC (2030). The full exploitation of the HL-LHC dataset will allow LHCb to perform the ultimate test of the CKM mechanism for quark mixing and $CP$ violation, and unique physics searches for phenomena beyond the Standard Model. Examples include measurements of $CP$ violating phases with ultimate precision, the measurement of the ratio ${\cal B} (B^0\to\mu^+\mu^-)/{\cal B} (B_s^0\to\mu^+\mu^-$) for a stringent test of supersymmetry models, studies of $b\to s\ell^+\ell^-$ and $b\to d\ell^+\ell^-$ transitions in both muon and electron decays, and the study of Higgs to charm quark coupling, as well as other physics opportunities that exploit the forward acceptance of the LHCb spectrometer. New detector components will improve the performance. The physics programme and the extensive ongoing R&D for new instrumentation are briefly summarised in this document.