From the author: An alternate WWII where magic and monsters exist, but you can still fight with submarines... mostly...
"You check those corners, sailor?" the Chief of the Boat barked. "Those lines are off by half a degree and our visitor doesn't materialize!"
"Re-measuring now, Master Chief!"
The COB was exaggerating, but I'd learned early in my naval career not to argue with a superior. If it wasn't likely to kill me, I just did it.
I placed my protractor on the dowstone panel we had strapped to the deck and re-checked all the angles in the chalked pentagram, then inspected every stroke of every rune around...