A group of robbers kill a security guard who was a former police officer and who, before his death, used the APB app. Meanwhile, Gideon redesigns a feedback chair - previously utilized in the aerospace industry - for use in the investigation room, and Murphy learns that her ex-husband, Assistant State Attorney Scott Murphy, may be watching them.

After a man goes to extremes to get justice for his daughter, Gideon and Martinez use new technology to investigate the case. Meanwhile, the assistant state attorney continues to interrogate Gideon and his ideas for the 13th district in the all-new.

After Gideon's father finds himself in trouble, he turns to Gideon for assistance. Meanwhile, Brandt and Goss work to track down the mastermind behind a huge grand theft auto case.

Gideon's life is threatened, so Conrad sends him home to get away from District 13. When the men after Gideon find him, Murphy and Gideon hide in his secret lab, where they become trapped. As they search for a way to escape, Murphy learns the main reason these men are after Gideon.

When Gideon is blamed for recent terrorist attacks, he and Captain Conrad work fast to track down the real culprit. But Gideon finds himself in a predicament, when Danny continues to use his technological skills to disrupt the city, leaving Murphy, Ada and the rest of the squad struggling to find a way to stop him. Discover who makes it out alive.