Over the course of the series, Michael and the organization investigate vampire-related activity, often involving medical experimentation. Individual cases involve a woman who may be pregnant with a vampire fetus, a vampire test subject with synthetic blood, and the outbreak of a disease related to vampirism. The vampires are organized, and appear to be moving toward a common goal; the organization must determine what their agenda is. Living and working in the shadows takes a personal toll on the organization's agents: Michael's relationship with Jack's fiancée (Colette Brown) is threatened by his need to hide the truth from her; Angie Marsh (Susannah Harker) must come to terms with the loss of her husband, who was killed by the organization after becoming a vampire; Fr. Pearse Harman (Philip Quast) is diagnosed with terminal cancer, but fears that leaving his post may doom the world to whatever fate the vampires have in store for it.