Berry and Hack are somehow able to escape from the Hyperverse that Phantom Zero pulled them into. But before long, Hack is apprehended by the customer center, who are investigating the Zero Phenomenon. The next day, Berry wakes up on the veranda of her apartment, and after trying to explain what happened, her friends point out to her that there is no evidence of Zero Phenomenon having occurred, much less of the kid she encountered. Not taking no for an answer, Berry decides to dig up proof behind the Zero Phenomenon.

Berry catches wind of a ramen cart that nobody knows the location of. In order to find it, Watson begins checking rumors from all across the island. Berry suggests that the detective club search for the cart, but the other members aren't interested. As Berry and Watson investigate the rumors, Watson receives a tip on the location of the cart. In pursuit of ramen, Hack, Berry, and Watson set out to find it.

Thanks to Doron and his drone friends, Berry, Hack, and Finn are able to reach Mark Twain, a strange facility floating in the sky. By using the Angelfish club card they had previously obtained, they manage to get inside, where Berry and Hack enter Mark Twain's rendition of the Hyperverse. What they discover appears to be a labyrinth. Knowing that all the secrets of Tom Sawyer island must be contained within, Berry and Hack start searching for Phantom Zero's identity.