Becoming Forest opens with Aishling-the young Irish woman at the heart of this story-as she visits her grandmother in California following her grandfather's death. Aishling finds her grandfather's journal and reads about a trip he made to India years ago to visit the original Bodhi Tree, the place where the Buddha found enlightenment.

At the end of the journal, she finds a letter addressed to her from her grandfather asking for her help passing along his message of "deep security" to her generation as they deal with the climate crisis and the uncertain future ahead. Aishling goes to India to follow in her grandfather's path to find a way of responding to his request. There she meets and falls in love with a young Buddhist monk, who is also on a quest. As they walk together along the roads of India, they gather unexpected and invaluable insights from each other and come closer to the answers they both seek.

Thirty years later, Aishling's daughter Tara is visiting her in Ireland. Tara is grieving the death of her father and also the destruction of the forests from drought and fire. She is also searching for a way to heal the burnout she and her friends are experiencing while working to combat climate change. Becoming Forest weaves together threads of Native American and Celtic spirituality with Buddhist understanding and connection to the natural world, creating a tapestry which holds both the despair and awakening of Aishling