Results are reported from an amplitude analysis of the B + → D + D − K + decay. The analysis is carried out using LHCb proton-proton collision data taken at √ s = 7 , 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb − 1 . In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the D − K + channel with masses around 2.9 GeV / c 2 , and a new spin-0 charmonium resonance in proximity to the spin-2 χ c 2 ( 3930 ) state