CaKFe4As4 is a new stoichiometric member of the iron-based superconductors (FeSCs) which is a superconductor below 35 K. In this thesis I outline how single crystals of this material are grown for the first time and their basic properties. I discuss how substituting Ni or Co for Fe stabilizes antiferromagnetism at the expense of superconductivity. I reveal how the crystal structure of CaKFe4As4 leads to the observed hedgehog spin-vortex crystal magnetic order instead of the magnetic structures adopted by the other FeSCs. Finally, I propose a series of new magneto-elastic couplings in this new magnetic structure.