A detect-o spy Lamp is a special light used to reveal messages written in invisible ink. Fern used one to read Persimmony Glitchet's letters that were written in invisible ink. There is a chance that the lamp is Horrendously Horrible Happenings merchandise, as Fern said that Victor Bronte used one in Book 5: The Malevolent Mailbox. Detect-o spy Lamp (normal).jpg|Off Detect-o spy Lamp (glowing).jpg|On