Born in Essex, James Abrahart—better known as JHart—spent his teens in Atlanta, GA, before decamping to LA, and is an expert at moving between worlds. As a songwriter, he has lent a sleek, synth-pop touch to country star Keith Urban and cast a rosy, '80s glow across Justin Bieber; he's written piano ballads and moody hip-hop bangers for Camila Cabello, and he's even led Martin Garrix from big-room house to soaring alt-rock. The common denominator? Every one of his songs brings goosebumps.