In His Majesty's Secret Service is the fourth episode of the fourth season of Nexo Knights, and the thirty-fourth episode overall. It first aired on August 24, 2017.
The Nexo Knights decide to use Clay to infiltrate the enemy camp but first Clay needs to learn how to be a good spy. Agent Shield, Jack Shield helps them with that.
- Nexo Power: Agent of Awesome
- The title is a parody of the James Bond film On Her Majesty's Secret Service.
- The Knights' acting skills seemed to have improved since their first performance in "The Golden Castle."
- Ruina Stoneheart's handshake to Clay affected his behavior for the worse in later episodes.
- Jack Shields says that even Clay's mother won't recognize him when he puts on the mustache, which is a reference to the fact that Ruina is his mother.
- When Clay saves Robin and tries to resist the Gargoyles, he strikes a Gargoyle with his sword but the Gargoyle doesn't disintegrate.