Dr. Peter Zak Books in Order

The Dr. Peter Zak books are where Hallie Ephron first made her mark in mystery fiction, writing with forensic psychologist Donald A. Davidoff under the shared name G.H. Ephron. These novels mix crime, psychiatry, and courtroom pressure in a way that feels grounded rather than flashy. Peter is not a hard-charging cop. He is a Boston forensic neuropsychologist and expert witness, the kind of investigator who gets pulled into violent cases because he understands memory, behavior, criminal responsibility, and the ways fear can distort what people think they saw.

He solves problems with brainpower, patience, and a feel for how people work.

That gives the series a different shape from a standard medical thriller. The tension usually starts with a mind in crisis: a surviving witness who cannot remember, a teenager whose addiction clouds the facts, a paranoid husband who may be ill or may be acting, a stalker case that keeps getting uglier, a bomber whose motives are hard to read. Amnesia begins with a woman who survives a shooting but wakes from a coma with her memory shattered. Addiction follows Peter into the murder of a colleague and the case against the colleague's troubled daughter.

The later books keep changing the psychological question at the center. Delusion asks whether Peter can trust a wealthy game designer accused of killing his wife. Obsessed starts as a stalking case around Peter's coworker Emily Ryan and turns darker as the danger spreads through a medical research setting. Guilt moves into bombings in Cambridge and the grim work of trying to profile a killer before more people die. Each book stands on its own, but together they build a series where the human mind is never just background detail. It is the engine of the mystery.

Peter himself gives the books their ongoing emotional pull. Before the series opens, his wife was murdered by a man Peter had helped in court, and that loss shadows almost everything he does. He carries grief, caution, and a little self-doubt into each investigation, which keeps him human. There is also a steady supporting cast around him, especially Annie Squires, an investigator who becomes an important part of his personal life, and Peter's sharp-tongued mother, who lives next door and keeps him from disappearing entirely into work.

Readers should expect smart, psychology-forward suspense rather than nonstop action. The science and legal angles matter, but the books stay readable because they are always tied to motive, relationships, and moral gray areas. If you like mysteries where diagnosis, memory, and perception can all be part of the crime, the Dr. Peter Zak novels are a strong series to read in order, starting with Amnesia.