Spike Darbyfield emotionally invests in only two things: her younger sister, Margie, and higher-end Japanese anime series. From others in her family, and from her colleagues, clientele, and most of humanity, Spike maintains an ironic or contemptuous detachment. When an Iraqi militant group kidnaps her sister while Margie is working for a human rights organization in Iraq, the crisis creates openings in the armor Spike built around her psyche over the years, allowing those who care about her to begin relating to her, and her to them, in different ways.

The author's organization Christian Peacemaker Teams (CPT), weathered its own hostage crisis between November 26, 2005 and March 23, 2006, when four of her colleagues were kidnapped in Baghdad and one, Tom Fox, was murdered. Some of the novel, Because the Angels, reflects CPT's desperate, blind attempts to keep these colleagues alive, but it also reflects the affirmation and solidarity CPT received from unexpected quarters and the grim humor that arose from dealing with absurd situations. (Incidentally, right after the kidnapping, Pulitzer Prize-winning journalist Seymour Hersh referred to CPT's work in Iraq as "Cutting edge."

Because the Angels, in the tradition of Marilynne Robinson's Gilead and Chaim Potok's Davita's Harp treats faith, and the interactions of secular and religious cultures, compassionately and analytically. Both Spike and her estranged father Otto, the secondary viewpoint character, undergo significant spiritual transformations in the narrative. Spike emerges from a shell constructed of her fictional passions and smug, twisted sense of humor and begins developing the ability to empathize with people other than Margie. Otto struggles with issues that arise from loving his children more than the rigid religious doctrines that have given his life meaning. In end, he lets grace win (mostly.)