Greg Zola

A serial rapist sends a letter to the squad announcing his return to Philadelphia after five years and his plan to strike again.

A mysterious death pushes Claire into the spotlight; Angela worries that Nathan will discover his true identity; an unexpected visitor haunts Matt; H.R.G. and Tracy join forces.

Claire goes to college; Ando and Hiro start a Hero-for-hire agency; Peter becomes an EMT; Matt reunites with his wife and child.

When a mathematician (Neil Patrick Harris) gets close to solving the Riemann hypothesis, a difficult math problem whose solution is worth millions, his daughter is kidnapped.

Antoine Batiste toys with martyrdom; Janette encounters an old nemesis and a new suitor; Delmond and Albert debut their album; Toni meets a new ally; LaDonna struggles with living with her in-laws.

Antoine's students show interest; L.P. Everett gets a new case; LaDonna is forced to move; Hidalgo finds a new angle; Janette's resistance slips; Albert receives news about his health.