The card is immediately revealed to be the High Priestess. One interpretation relates to the unconscious and/or withdrawal from involvement. Mystery and secrets seems to be a common theme, and wikipedia also adds love and relationships. This time the correct interpretation is: all of the above.
The Secret Door opens with the Duke of Freid holding court. He is sympathetic to Van's lost kingdom, but not impressed with Allen.
An attempt by Chid to intervene on Allen's behalf is met with some harsh criticism.
On the other hand Millerna, who is becoming more impressive in every episode, does successfully intervene. Her astute analysis of Zaibach's intentions don't hurt. However it may be partially due to Freid having a soft spot for the sister of his late wife.
Folken briefs Dornkirk on the information about Hitomi. Dornkirk is intrigued, wants to see Hitomi, and mentions having come from Earth himself at one time.
Freid is gearing up for war as Millerna redresses Allen's wound. Allen is reminiscing about another blonde and is largely ignoring Millerna. Some light humour with Merle and the moleman ensues.
Hitomi is still seeing the vision of Zongi's death, and is not handling it well. There is a reason for this that I'll discuss later, but it is significant.
Merle brings Hitomi to Van who is spending some time sharpening Escaflowne's sword with the assistance of Allen's goon squad (hey, it's a big sword).
Being surrounded by the instruments of war is not a good time to ask an already upset Hitomi to try and see the direction from which Zaibach will attack. Hitomi doesn't want to see the visions, and asks to be left alone.
Reminders of her previously harmless readings on Earth don't help her state of mind.
Later that evening Millerna is out for a stroll and finds an Asturian villa. Inside Duke Freid is pensively looking at a full length portrait of Marlen. It turns out that because this villa was where Marlen lived prior to her wedding, Duke Freid had brought the villa to Freid and rebuilt it in the grounds of the palace.
Despite his earlier, quite harsh appearance, Freid begins to emerge as something of a romantic in this scene. It does make his quite harsh dismissal of Chid earlier harder to understand.
Millerna slips into memories as she finds a music box that she remembers from her childhood and a secret compartment with a book that she didn't know about.
At this point there are two other storylines running in The Secret Door. One is Van attempting to master dowsing by shooting arrows with his eyes closed, and the other is Chid seeking reassurance from Hitomi about whether he will be worthy to be the Duke after his father.
Hitomi then spontaneously volunteers to do a reading for Chid, and I consider this to be a serious flaw in this episode. It is an example of breaking characterisation for plot convenience, and it almost ruins the episode.
An alternative of Chid insisting on a reading to gain reassurance with Hitomi reluctantly agreeing because she doesn't want to let a child down would have worked much better here.
Millerna begins reading Marlene's diary as it reveals her growing romance with Allen. Meanwhile Hitomi's reading for Chid is leading her to the same conclusions as Millerna.
Millerna's expression when she reads the entry where Marlene comes right out and says that Allen is Chid's father is priceless. Hitomi on the other hand doesn't react much better but does manage to keep that bit to herself.
The Zaibach armies arrive and advance on Freid. With something close to 10,000 Guymelefs and 60,000 troops their presence is quite hard to hide.
Freid holds council and there is a reference to a Book of Lions and the "duty of those born in Freid".
Freid mobilises to defend as Millerna confronts Allen in the hangers.
But at the last second Duke Freid intervenes and declares Chid to be his son. He clearly knows the truth but is officially denying it and, also officially, recognising Chid as his heir. More complications for an already difficult to understand character.
As Dilandau's dragonslayers sneak up on the capital the end credits roll.
Overall this is a solid episode of character development. Millerna, Freid, Allen are all affected by Marlene's shadow as the secrets come out to play.
The cliffhanger of the pending invasion is nicely timed, and the episode feels complete in and of itself.
Having said that, Hitomi's sudden willingness to do a reading is a (fortunately) rare example of plain bad scripting in Escaflowne and one for which there is no real excuse.
Day 1 - Fateful Confession / The Tower
Day 2 - The Girl From the Mystic Moon / Ace of Serpents
Day 3 - The Gallant Swordsman / Death
Day 4 - The Diabolical Adonis / The Hanged Man
Day 5 - The Seal of the Brothers / Judgement
Day 6 - Capitol of Intrigue / Justice
Day 7 - Unexpected Partings / The Chariot
Day 8 - Sub vs Dub
Day 9 - The Day the Angel Flew / Temperance
Day 10 - Memories of a Feather / Ace of Birds
Day 11 - The Blue-Eyed Prince / Knight of Beasts
Day 12 - Prophecy of Death / The Devil
Day 13 - The Secret Door / High Priestess
Day 14 - Red Destiny
Day 15 - ???
Day 16 - Dangerous Wounds
Day 17 - Lost Paradise
Day 18 - The Guided Ones
Day 19 - The Edge of the World
Day 20 - The Gravity of Destiny
Day 21 - Operation Golden Rule of Love
Day 22 - False Vows
Day 23 - Reaction of Fortune
Day 24 - ???
Day 25 - The Black Winged Angel
Day 26 - Storm Premonition
Day 27 - Fateful Decision
Day 28 - Zone of Absolute Fortune
Day 29 - Eternal Love
Day 30 - Looking Back at The Vision of Escaflowne