I think they are one and the same, completely identical to each other....ложь is just understood as lies?
No way! Don’t even think about it!wouldn't it be в лжи anyway = prepositional case?
Well, it might look something like that in a similar sentence, say: “спрятавшись во лжи, я не могу быть в мире с самим собой”, but note the additional o in во лжи. I don’t know if they teach you this in grammar books, but we add the "o" to make the sound flow. Without it it’s almost a tongue-twister whereas in в грязи, for example, your в sounds just fine, all in accordance with the rule you may have made your assumption on.