Where does Zeus steal the 5 sacred items on Mythology island?

Once you have all five items, you take them back to the Tree of Immortality, where Athena helps you decipher the message written on them. Once it is found, Zeus appears and steals the items (and does not give you immortality or anything else).

Once the items are stolen, Hercules will agree to help stop Zeus, but you will need the Touchscreen Mirror from Aphrodite's test on the beach in Poseidon's realm. Hercules is not in the mood to walk very far.