In 1787 Lieutenant Thomas Rooke sets sail from Portsmouth with the First Fleet and its cargo of convicts, destined for New South Wales. As a young officer and a man of science, the shy and quiet Rooke is full of anticipation about the natural wonders he might discover in this strange land on the other side of the world. After the fleet arrives in Port Jackson, Rooke sets up camp on a rocky and isolated point, and starts his work of astronomy and navigation. It's not too long before some of the Aboriginal people who live around the harbour pay him a visit. One of them, a girl named Tarunga, starts to teach him her own language. But her lessons and their friendship are interrupted when Rooke is given an order that will change his life forever. Inspired by the 1790 notebooks of William Dawes in which he recorded his conversations with a young Gadigal woman, The Lieutenant is a story about a man discovering his true self in extraordinary circumstances.