Deep Down is a novel about the dangers and hardships of life in a Cornish tin mine in the mid-19th century. The story follows Oliver Trembath, a young doctor who comes to the mining town of St. Just to work at the Botallack mine. Trembath is initially horrified by the conditions in the mine, but he soon comes to admire the courage and determination of the miners. The novel explores the themes of courage, friendship, and community. Trembath learns to appreciate the simple things in life, and he comes to see the miners as his friends. He also witnesses the dangers of mining, and he comes to understand the importance of safety. Deep Down is a historical novel, but it is also a work of fiction. Ballantyne uses his imagination to create a vivid and suspenseful story. The novel is full of action and adventure, and it provides a glimpse into a way of life that has long since disappeared.