Roark leaves architecture school, apprentices himself to Henry Cameron, and then sets up his own practice. The "call" here is basically Roark answering his own professional calling in life, and we follow him on the start of his career as an architect. His professional debut is contrasted sharply to that of fellow architect (and professional schmoozer) Peter Keating.
Roark keeps up the good fight in his professional life and manages to get something of a personal life through his screwed-up relationship with the love of his life, Dominique Francon.
Things go from bad to worse as Roark faces new professional challenges and loses Dominique due to her fears. Roark has to go on trial for the Stoddard Temple, and Dominique marries Peter Keating.
Dominique leaves Keating and marries Gail Wynand. The book focuses heavily on the triangle springing up between Wynand, Roark, and Dominique. The nightmarish power trip of Toohey and the drama of the Cortlandt House project also take center stage.
Thrilling Escape from Death and Death of the Monster
Roark blows up the Cortlandt House, goes on trial, and survives to go on and marry Dominique.
Roark triumphs when things look bleak and he and Wynand manage to knock Toohey down a few pegs. Dominique also frees herself up and marries Roark, and Roark of course keeps on building, which is his real triumph over Toohey and his crowd.