In episode 6, titled 'And the House of Cards,' the Tarot deck plays a significant role when Madam Visconti uses it to reveal that the 'Devil' card represents the actual Devil, who has been trapped in a murder mystery mansion. This sets off a race against time for the Librarians to prevent further harm.

The team investigates the murders by questioning various guests. Connor interrogates Mortadella, Vera, and Phillip, while Lysa questions Yvette. This process helps them unravel the mystery behind the Devil's actions.

The mansion serves as a setting where the Devil is trapped and is carrying out a series of murders. It is designed to protect the outside world from the Devil's influence, but he is determined to escape by killing those who imprisoned him.

Lysa's character evolves as she learns more about the world and her role in The Library. Her interactions, particularly an argument with Vikram, highlight her growth and the complexities of her relationships within the team.

The conflict between Vikram and Lysa arises from Lysa's connection to Vikram's deceased lover from 200 years ago. This historical tie creates tension and emotional depth in their relationship, making their interactions more complex and emotionally charged.