Captain America descends by rope into the catacombs deep beneath the streets of Manhattan. He is coming in response to a signal he is receiving on a transmitter he carries. Reaching a level area, he discovers the skeletal remains of the Mole Man’s servitors, dead by violence. Suddenly a hail of spikes comes at him from two directions and only his amazing agility enables him to leap out of their path…onto a huge trapdoor which opens, dropping him toward a lava pit. He again leaps toward the open floor panel but spikes suddenly protrude from it…affording him a handhold. He climbs back to the chamber—then a wall starts to drop into place; Cap manages to slide quickly under the descending barrier—only to be trapped by a second wall. Then the spiked ceiling slowly moves down toward him…and more spikes appear in the floor. Cap manages to wedge his shield into place to halt the ceiling’s descent while he uses a blasting cap in his kit to blow open the wall and escape the death trap. He finds himself in a ceremonial chamber with the corpses of three men, one woman…and a dolphin. Deciding to worry about that later, he follows the emergency signal to a deep pit which lies beneath a hole in the ceiling. He descends into the pit in the face of a violent updraft until he finds a ledge. On the ledge is a coffin-shaped box. He pries open the lid and discovers a panicked and grateful Diamondback, who had given him the transmitter back in issue #344. She explains how she had stumbled onto a heist pulled by Batroc the Leaper and his cronies (last issue) and was sealed inside the box with the stolen skeleton of Ulysses Bloodstone and dropped in the pit. Cap recovers the skull and they climb up out of the pit.
On Avengers Island, the Wakandans have just delivered his modified Quinjet. Cap and Diamondback arrive but he has no time to look at it or to meet the pilot Colonel John Jameson before he rushes off to research the mystery. Cap learns about monster hunter Ulysses Bloodstone and the magical gem he wore on his chest; meanwhile, Fabian Stankowicz has attached a radiometer to the skull, making it a detector for the fragments of the Bloodstone. Cap and Diamond rush for the new jet and have Col. Jameson take off for the first destination: the Amazon jungle. Reaching that remote area, Cap and Diamond (who won’t admit she has never used a parachute before) jump into the wilderness and are soon captured by Inca tribal warriors. They are taken to a hidden pyramid where the chieftain, wearing a Bloodstone fragment in his ceremonial mask, orders the Wheel of Death raised. A massive stone wheel, built into the floor, has Batroc, Baron Zemo, Zaran, and Machete shacked to it. As Cap prepares to move, he and Diamond are suddenly felled by blowdarts, and they sink to the floor….