What is the prepositional phrase in sentence Upon arrival was whisked into a secret chamber?

The prepositional phrase in the sentence "Upon arrival was whisked into a secret chamber" is "upon arrival".

Here's why:

* Prepositional Phrase: A prepositional phrase starts with a preposition (like "upon", "into", "with", "around", etc.) and ends with an object of the preposition (the noun or pronoun that follows the preposition).

* Preposition: "Upon" is the preposition.

* Object of the Preposition: "Arrival" is the object of the preposition.

Let me know if you have any other sentences you'd like to break down!