We pick up here just a few moments later, with Antonia, Don José, and Mrs. Gould hanging out in the carriage and General Barrios stopping by to say hello to Mrs. Gould. While all this was going on, Antonia was checking out some dude standing nearby. We soon learn that his name is Martin Decoud.
We then get a little information about how Martin, who was born in Sulaco but had lived a lot of his life in Europe, ended up coming back home.
He had been living in France until he was recruited to serve on the "patriotic small-arms committee of Sulaco," a position he was offered because he was likely to be loyal to Don José (his godfather) and his political/business associates.
Martin's appointment and his activities took place behind the back of General Montero, who at this point was apparently still part of Ribiera's government but not trusted.
Martin's job was apparently to get arms into the hands of General Barrios. He decided to deliver them himself—he made an excuse about wanting to see his job through to the end, but his sister suspected his motive was to see Antonia.
Whatever his motive, he traveled to Costaguana to deliver the arms. Before he could arrive, however, Montero had already turned against Ribiera.
Martin had been planning to return to Europe right away but, after seeing Antonia, seemed to change his mind. So, he stuck around.
Because he had demonstrated some talent for writing and journalism previously, Martin gets tapped to run the anti-Monterist newspaper Porvenir (to combat the claims being made in the pro-Monterist press, naturally).