In episode four of the Beyond the Horizen podcast, the focus is on security within the Horizen ecosystem. The hosts are joined by special guest James Shuman, Head of Security at Horizen Labs, and co-host Ben Sherman. They discuss the recent launch of Horizen EON's permanent test net called Gobi, which is designed for testing and launching smart contracts on the mainnet. Additionally, they introduce a bug bounty program co-hosted with Immunifi, offering up to $75,000 in bounties to the community.