S18, E1: Detective Cyrus Lupo (Jeremy Sisto) leaves terrorist regions to return to his own family terror at home. After four years abroad, Detective Lupo (Sisto) returns to the United States to find his brother committed suicide by lethal injection because of his incurable illness. Before the case is closed, another man is found dead, having killed himself in an identical fashion. Lieutenant Van Buren (S. Epatha Merkerson) permits Lupo to work the case alongside fellow Detective Ed Green (Jesse L. Martin). Lupo and Green are suspicious of a recent parolee formerly known as "Dr. Death," and through further investigation they are inclined to believe "Dr. Death's" daughter (guest star Marin Ireland) could be a follower of her father's work. Also starring: Sam Waterston, S. Epatha Merkerson, Linus Roache, and Alana De La Garza.