Who or what is Unit 23? Luke Cage must lead his new Thunderbolts deep below on their deadliest mission and face the horrors that mankind can become. While S.H.I.E.L.D. was shut down, a now-missing government squad was charged with guarding a cavern full of impure Terrigen crystals...and if these powerful elements morph Inhumans with wild transformations, what in the world will they do to humans? It's a volatile environment--and a bad time for a challenge to authority from The Juggernaut!
Ghost continues to be attacked by the human-looking female troll from last issue. Crossbones takes her out just in time by shooting her in the ear with a tranquilizer dart. Back at Thunderbolts Tower, they find out from Valkyrie that the girl is Asgardian. Her mother had been captured by the Magzi, the most feral troll tribe, who raised her. Attempts to assimilate the girl, named Gunna, into regular Norse culture were unsuccessful. Valkyrie offers to take her to the new Norse home, but Warden John Walker refuses since she killed U.S. citizens. Valkyrie and Walker argue before Luke Cage suggests they consult Steve Rogers. Valkyrie accepts and leaves Gunna in Walker’s custody, and Songbird will orientate her to the Raft when she wakes up.
The next morning, Cage briefs the team on their next mission. A squad of SHIELD agents was dispatched to investigate a supposed new strain of Terrigen crystals, and seal off the cavern if they were present. After the first team didn’t return, a U.N. team followed and also failed to return. The Thunderbolts are equipped with oxygen supplies or nose filters to prevent exposure to the Terrigen mists. The team transports to the cavern in New Guinea via Man-Thing. Cage tells Mach V to watch after Man-Thing. The team heads down one tunnel, where sensors indicate the crystals are, while Mach V follows a wandering Man-Thing down another tunnel. Amidst corpses at the crystal site, Ghost finds data gathered by the SHIELD team and learns there is a vein of uranium ore underneath the crystals – the uranium is corrupting the Terrigen mists. Suddenly, Cage gets a distress transmission from Mach V and tells the team to go outside and wait for him. Juggernaut and Crossbones argue about whether they’re being tested again, while Moonstone heads after Cage right away. Before leaving, Crossbones finds something left behind by the SHIELD agents. Cage finds a helmetless Mach V being attacked by a large, severely mutated creature. Mach V warns Cage that the creature is toxic. The creature attacks Cage and the toxins blind him. Ghost determines that the creature is the lost SHIELD agents. Moonstone also falls to the creatures. Ghost overrides Mach V’s armor, takes it over, and saves Moonstone. However, there are many more creatures in the cave. Juggernaut plows through several of the creatures, but is covered with their toxic remains and passes out. The conscious members of the team are left to deal with the creatures: Crossbones, now with a minigun left behind by SHIELD; a Ghost-controlled Mach V; and Man-Thing.