In the premiere episode of Iron Girls, titled "The Beginning," viewers are introduced to four determined actresses: Jin Seo Yeon, Uee, Seol In Ah, and Park Ju Hyun, who embark on an ambitious journey to train for an Ironman triathlon. With only four months to prepare, the episode highlights their initial struggles as they confront the physical and mental challenges of intense workouts.

Jin Seo Yeon emerges as the team's motivational leader, drawing on her passion for fitness to inspire her teammates. Uee, a former professional swimmer, showcases her superior athletic abilities, while Park Ju Hyun, initially the weakest link, gradually finds her determination. Seol In Ah surprises everyone with her hidden athletic talent, transforming into a competitive force during training.

The episode also features Kim Dong Hyun, a former UFC fighter, as their coach, guiding the women through rigorous training sessions. As they navigate their fears and doubts, the episode emphasizes themes of perseverance, teamwork, and personal growth, setting the stage for an inspiring and entertaining season ahead.