Accidentally let party wander into a high level situation, how do I help them get out without cheesing?

TL;DR – due to poor planning on my part in my sandbox-esque game, a party of four Level 5s (fighter, warlock, non-healer bard, wizard) is about to wander into a high level situation and I’d like them to not die while still letting them accomplish something.

Here’s the situation.

The party recently emerged from the Feywild to find that two months had passed on the outside. They ended up near the capital city. Okay, cool. I prepare some rumors they can dig up so they can help find out what they missed. One character in particular has a lot of backstory in the capital, so we hashed out some of the relevant NPCs.

In an attempt to set up and highlight how tensions are escalating in the kingdom with the threat of war on the horizon, as well as to set up an NPC Big Bad later, I let them find out that some people around the capital have been “disappearing” on order of the Queen’s Spymaster because they were suspected of being spies for the enemy empire. The Queen herself has been rumored to be ill and has definitely become hard to get a hold of. One of the NPCs who disappeared was one of a character’s school friends, who we’d hashed out the existence of between sessions.

Now, these disappearances were all on trumped up charges. The character who’d spent the most time in the capital actually is a spy for the enemy empire and would know this. She was adamant – and correctly so – that her friend was innocent.

What I expected to happen – and this is on me – was that they’d hear that the second most powerful person in the kingdom had a direct hand in these events and get out of town. The entire group is Level 5. I expected this entire setup to be set dressing for stuff they’d deal with later. It’s not like they don’t have a lot of side quests and leads to chase down elsewhere.

Instead, they resolved to do whatever they could to rescue this girl and get to the bottom of the situation.

Here’s what I know that they have no feasible way to find out at this point:

  • The Queen’s Spymaster has defected – she’s orchestrating events to deliberately try and undercut faith in the government as well as generally sow chaos
  • She’s not operating in the good faith the group assumes she is. This is not an innocent mistake or paranoia they can assuage.
  • The Queen’s Spymaster is actually one of the six heroes of long ago legend and is thus a Level 15 assassin living in secret.
  • The Queen herself is not even in the city at this time, and (as a high level sorcerer) she’s left a simulacrum in her place to help allay suspicion.
  • The group has rolled really badly on Perception checks to see if they’re being tailed and they are, in fact, being intermittently tailed.

    I don’t want to punish them for jumping in to this plot with both feet. I don’t want to stonewall them from finding this missing girl since they’re super invested in doing so, and they know she’s still in the city.

How can I help arrange things so they have a chance of succeeding while still putting them in a reasonable amount of danger?

Wander around airport connecting flight Schipol

I am flying on a flight from London – Schipol soon and then outbound to Moscow.

My layover time is around 3 hours. In this time I would like to wander around the airport, look at the shops and hopefully have something to eat.

Last time though, when I flew the same route, I was stuck in the connecting flight lounge and couldn’t look around without re-entering the airport.

So my question is will I be put in the connecting flight lounge again or will I be able to wander around?

And if I am put in the connecting flight lounge is there any point for me to re-Enter the airport?