Book and Tarka gamble for isolynium at a casino while Burnham tracks them and finds clues about the anomaly's source.
Tarka needs the rare material isolynium to finish his weapon, and Burnham expects Book to look for it on the black market. Rillak forbids pursuit, but Admiral Vance quietly sends Burnham to find 10-C's location and the isolynium first.
At a casino on Porathia, the dealer Haz Mazaro offers Book and Tarka the isolynium if Book catches a cheater. Burnham and Owosekun buy charts that point to 10-C, and Owosekun fights in a ring to raise money. Book wins the isolynium in a card game, but Burnham secretly plants a tracker on it. The charts reveal a huge artificial hyperfield beyond the galactic barrier, apparently powered by boronite the anomaly mines from planets. Sean Cochran wrote the episode.