Series One is the first series of Downton Abbey. It premiered on ITV on 26th September, 2010.
Series one begins at an English country estate called Downton Abbey in April of 1912, with the sinking of the Titanic. It focuses on the lives of the Crawley family and the servants on the estate until August of 1914, with the declaration of the First World War. Two of the main storylines are who will inherit Downton after the current Lord Grantham Robert Crawley, and Lady Mary Crawley and her desire to find a suitable husband.