Holmes and Watson enter the world of nuclear security when they investigate the murder of an ex-Yakuza gang member. Captain Gregson is blindsided by a stunning personal confession from his police sergeant daughter.

Kara makes a major life decision. Meanwhile, J’onn finds out that special DEO-caliber guns have hit the streets of National City.

The Adams Fosters comes together for some major celebrations, set one year after the spring finale.