[quote=@Guardian Angel Haruki]
[@Lurking Krog] Would you like a Perception or an Investigation check?
[/quote]

Persuasion and/or investigation. Persuasion will help lower the DC  of the investigation check, high enough you would gain more access to the storage area than just the initial entrance.

Minor correction, it is not Delgren at the common hall, just the purple man whom Delgren had mentioned earlier.