Someone was looking for information on the death of Achilles and the birth of Hephaestus (Vulcan to the Romans). Achilles was wounded in the one spot on his body that had not been made immortal. This was the heel by which his mother, the Nereid Thetis, held him as she dipped him into the River Styx to confer immortality.
It was also Thetis who rescued Hephaestus from his fall from the heavens. Hephaestus was cast out either by his mother or Zeus. Hephaestus is sometimes said to have had only one parent, Hera, who gave birth to him after Zeus gave birth to Athena, although the chronology there is confusing since it was Hephaestus who cracked open the skull of Zeus to let Athena out. When it is said that Hephaestus was born to Hera alone, Prometheus is said to have struck Zeus' skull.
For more on Achilles, see Legendary Heroes, Achilles, Hercules, Theseus, and more.
For information on Hephaestus, see Hephaestus.

There is a later link between Hephaestus and Achilles, via Achilles' mother Thetis. She asked Hephaestus to forge a shield for her son to use during the Trojan War after Patroclus died wearing Achilles' old armor. He did. The Iliad Book XVIII contains a description of the Shield of Achilles.
Outline of the Iliad