Despite continuous training for his next encounter with Zoom, Barry's speed ceases to improve. Harrison has only one resort left, a serum he once tried to develop for Jay (The Earth-2 Flash). With Caitlin's help he succeeds, but Jay resolutely warns against its use. Meanwhile, Egyptian immortal Vandal Savage comes to Central City to slaughter the latest reincarnation of warrior priestess Chay-Ara, known to Cisco as his girlfriend Kendra. Barry solicits team Arrow's help in protecting her while he as The Flash, alongside Green Arrow, find dealing with the Egyptian deity difficult.
—statmanjeff