Hainan Island, located at the magical 18 degrees north latitude, features mountains and seas intertwined, with an extremely rich biodiversity and breathtaking scenery. It is just like a meticulously crafted garden by Nuwa. There are nearly 200 species of rare and endangered plants here. Many plants that are hard to find elsewhere can thrive in this tropical primeval forest.

The protagonist, Lin Mu, is a top-notch botany student from a prestigious university in the country and once had a bright academic future. However, a series of unexpected changes came one after another. Struck hard by life, as a socially anxious person, he resolutely and voluntarily returned to his hometown and became a forest ranger. Since then, day after day, he has walked along the desolate and rugged mountain paths, carefully visiting every plant and quietly listening to the sounds of every animal, repeating the daily work that his father used to do. What he guards is not only this forest but also the world of plants that his father defended with his life.

It was not until the unexpected arrival of Ci Yingxue and the botanist Wen Heng that Lin Mu's originally peaceful and lonely life was disrupted. Their appearance opened a brand-new door of cognition for Lin Mu, enabling him to have a much deeper understanding of the plant friends that had always accompanied him. In the frequent communication and collaboration with the two of them, Lin Mu gradually overcame his inner barriers, stepped out of the narrow world where he had imprisoned himself, and his heart became increasingly relaxed.

During the process of jointly protecting endangered plants and outwitting the lawbreakers who steal plants, Lin Mu reignited his passion for botanical research. With his solid professional knowledge and unremitting efforts, he laid an important foundation for the protection of endangered plants in the tropical primeval forest. After going through numerous challenges and trials, he finally grew into a senior botanist, realized his self-worth, and also made a crucial contribution to safeguarding the ecological treasures at 18 degrees north latitude.