Roger Casement plays a central role in the formation of the Irish Volunteers in 1913. One of the public faces, he travels around Ireland to raise support for this nationalist organisation. As his political commitment grows, he also masterminds the importing of guns for the Volunteers into Howth outside Dublin.

World War One breaks out and nationalism is split in two and Roger leaves Ireland. Throughout this time, he is assisted by his lover, Adler Christensen but his mental health is going downhill.

Hearing of plans for the Easter Rising in 1916, he returns to Ireland on a German submarine. But the British authorities are on his trail.