Four heroes are being flown to appear on the radio show "Heroes" when their jet crashes in a storm. Miraculously, all four survive unharmed, even down to a working watch. Since they are "living on borrowed time", they vow to make the best use of it, taking risks to benefit others, challenging the unknown. In their first official case, they are summoned by Morelian, a descendant of Merlin, to open four chambers of a dangerous alchemist's box and "witness things not seen on this Earth since the dawn of Man!"; The Challs relocate the box to a tropical island and draw straws. The first chamber releases a "Dragon's Egg" that hatches a stone giant of legend. It wreaks havoc on ships, even resisting an atom bomb. What to do? While back on the island, Rocky's ready to crack the next chamber.; Picked up by sailors, Red returns to the island to find the second chamber open and Rocky frozen stiff. The menace is a sentient freezing sun from parts unknown that sucks up all heat, freezing people. Alone, Red cobbles a vacuum chamber and lures the sun inside, trapping it. Meanwhile, out on the water, Prof realizes that, since the Dragon Seed Giant can't be harmed by anything, it must be a thought, so he "thinks" it out of existence. All the while, Morelian flies overhead, watching.; The third menace is a tube that releases a whirling weaver. Out of control, it spins ribbons that snarl entire cities. The Challs pursue, then discover a dial on the weaver's tube and slow it to a halt. Returning to the island, they find Morelian has opened the fourth chamber for his own selfish reasons. He got a diamond ring of immortality: he'll live forever. Except the inscription on the box is vague, "contained in me, find immortality". Morelian flies off, but his plane stalls and crashes, killing himself and destroying the box. The box granted immortality: the ring was certain death.