A paradoxical argument
An argument is called sound if it is deductively valid and its premises are true. Now consider the following argument, which I'll dub 'argument Z':
1. If the conclusion of argument Z is true, then argument Z isn't sound.
2. If the conclusion of argument Z is not true, then argument Z isn't sound.
Therefore: Argument Z isn't sound.
Is argument Z sound? (If not, which premise is false?)