In this episode the data from a murdered researcher's computer is recovered after being "wiped". In the clip, Charlie uses the basics of magnetism and binary encoding to explore how the two are combined to store data on hard disk drives and how this data might be recovered after being overwritten with other data.
Since Hacker has a secret device that can listen in on their conversations, Matt, Inez, Jackie, and Digit need to create a way to communicate with each other without Hacker knowing what they are saying. They decide to create a code and an accompanying ruleset so that both the sender and receiver can understand the message. Inez suggests using the page number, line number, and word number within the line of Digit's book, The Cyberchef, to communicate.