What metaphors are used in Night Prey by John Sandford?

There is a metaphor of sacrifice throughout the novel. The ultimate sacrifice in Night Prey is that of Meagan Connell when she plummets to her death with the killer, Robert Koop. During a struggle and while attempting to help her partner, Lucas Davenport, Connell and Koop become entangled and topple over the railing of Sara Jensen's balcony. Lucas tries to save Connell, even managing to touch the leg of Koop before the two fall beyond his reach, but is unable to change the course of events.