This article examines the research of Louis J. Mordell on the Diophantine equation y 2 − k = x 3 as it appeared in one of his first papers, published in 1914. After presenting a number of elements relating to Mordell's mathematical youth and his (problematic) writing, we analyze the 1914 paper by following the three approaches he developed therein, respectively based on the quadratic reciprocity law, on ideal numbers, and on binary cubic forms. This analysis allows us to describe many of the difficulties in reading and understanding Mordell's proofs, difficulties which we make explicit and comment on in depth.