Imaculata
Hero
If I were a player in that adventure, I supposedly agreed that we're interested in discovering the mystery the hard way, so I would not play a PC capable of spoiling it all with a click, or I would pretend to forget I could click that button.
I think this is also a fair point. You either run with it and design the mystery around the spell, or you agree not to allow the spell.
When I started my pirate campaign, I agreed with my players that they would not choose any race that could naturally breath underwater, or use flying spells. I explained to them that the campaign was meant to revolve around the threat of water and I didn't want that threat diminished so easily. I wanted them to do a lot of sailing, and to deal with water in some manner, by using what the game had to offer. Spells that provided underwater breathing however, or shape shifting into a shark, were perfectly fine.
I think it can work fine if you can get your players on board with such an idea.