Blake takes a pistol to the Ballarat observatory to meet Major Alderton. The Major was using Mei Lin to get Blake to return to the army for service in the growing Indo-China war. As the sky darkens during the eclipse Alderton is stabbed in front of Blake, but the murderer is not known. The operator of the Observatory is suspected, as is Blake. When a sharp instrument is found in Mei Lin's room, Blake is arrested. From his cell in Ballarat, Blake works on solving the murder to avoid being taken to Melbourne by the Special Branch and then Mei Lin confesses to get Blake released. She is nearly murdered by the true murderer, saved in time by the police. As the murderer is escorted out for military trial, he in turn is murdered by a man who disappears.