When “King’s Knight” is Normal Summoned, its Trigger Effect starts a chain if “Queen’s Knight” is on the field. If the opponent chains “Torrential Tribute” to destroy “King’s Knight” and “Queen’s Knight” you still Special Summon “Jack’s Knight”.
The effect of “King’s Knight” can only activate if it is Normal Summoned. Not if it is Flip Summoned, Special Summoned, or Set.