Guy Hastings, an Alcatraz guard, reappears. Although a good man, Hastings is being asked to do bad things and will come face-to-face with an old acquaintance.

When Hauser, Madsen, and Soto track former inmate Paxton Petty, a landmine bomber who has returned and is placing bombs throughout populated areas of San Francisco, methods of the past are applied to the present.

Madsen and Hauser hunt down Johnny McKee, a former Alcatraz inmate and vicious killer with a background in chemistry. It’s a race against time before McKee horrifically poisons more innocent victims. Meanwhile, more details emerge about Madsen’s grandfather.

Herman and Pinky Ames, who almost escaped in 1963, return to Alcatraz in the present day and find something strangely wrong.

Sonny Burnett, a man with a dark side, who became extremely violent while at Alcatraz reappears.

Clarence Montgomery was the only innocent man in Alcatraz, but he's returned and is committing crimes.

Rebecca, Doc, and Hauser set out to capture musically-inclined serial killer Webb Porter, an unknown ’63 that returns more violent than ever.

Doc and Rebecca close in on a man who may be the key to revealing the secrets behind all the returning criminals. Meanwhile, Hauser makes a discovery beneath the halls of Alcatraz that brings him ever closer to the truth.

Revealing doors are opened and lives hang in the balance as Rebecca will stop at nothing in pursuit of the man who killed her partner.