City of the Dead (1) - S2.E1

McCallum, finding himself unable to cope with his estrangement from Joanna and the pressures placed upon him by his work, walks away from a crime scene.

McCallum's absence results in Maloney working an extra shift, even though it means she will have gone without sleep for more than 48 hours. When she attempts to drive to the crime scene McCallum abandoned, Maloney strikes an elderly man with her car. Believing herself guilty of negligent homicide, Maloney does not try to defend herself against the charge. McCallum, however, works feverishly to find evidence indicating Maloney was not responsible for the man's death.