In Yokohama, Japan, one thousand feet below sea level, a bomb is set to detonate in 24 hours. Meanwhile, in Gotham City, a team of ninja assassins attacks Katanna, stealing her sword and leaving her for dead. But does their desire for her sword confirm Katanna’s beliefs that it contains the soul of her dead husband? The ninjas will have to work fast to find out, as they’re not the only ones willing to shed some blood to be in possession of the weapon. And in order to get the sword back, the Birds of Prey will have to travel to Yokohama to track it down … with only 12 hours left until detonation.