Viewers of BBC's Vigil starring Greenock's Martin Compston will know that the setting for the crime drama is pretty good with how they make the crew - and us at home - feel claustrophobic.
But as the drama unfolds into who killed Craig and his girlfriend Jade, people have been curious to find out how and where Vigil was filmed.
Glaswegians will know that the City Chambers and the old City of Glasgow College building were just a few local hotspots to be featured on the hit BBC One series, however now the RAF has gotten involved and teased that is actually filmed on a submarine.
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During the third episode, RAF Luton 'revealed' that Vigil is in fact filmed on a real submarine called HMS Sinky - yes you can see where this is going - which is how they were 'able to film the scarily claustrophobic scenes'.
Tweeting a tongue-in-cheek detailed 'map of the sub', they said: "SPOILER ALERT: Many of you have messaged to ask if Vigil is filmed onboard HMS Sinky and if submarines really are that big! We can confirm that it is filmed onboard HMS Sinky and have attached a handy "Visitors Guide to HMS Sinky" that will help you through tonight's episode."
Vigil viewers took to Twitter to share their favourite part of the joke submarine image citing the food hall, gift shop and mini Waitrose at the top of their lists.
In addition to the supermarket and gift shop, which were places on board specifically for the cast the RAF teased, 'facts' were also revealed about the ship itself.
The sub which is the length of 192 London buses and the weight of around 75 football pitches, is said to be jokingly powered by 5,000x AA batteries and has 15 AA batteries as back up should anything fail.
If you need any WiFi, you're out of luck as it only has 2 mps - but the good news is you can get the same Markus Chairs as the real Vigil crew used from IKEA - though they are having supply issues at the moment so maybe wait until things are back to normal.
The RAF did a class job of having us BBC Vigil fans on - have a look at the map for yourself and tell us your favourite part in the comments - we can't stop laughing!
