X-Men #21

"Exogenous" Part 4 of 5!

As the race X-Men, to find the origins of the threat that emerged from deep space, they discover that there is more to the conspiracy at work ... one that may have its roots close to home!

What links a mysterious agent of the brand in order Providian?

How could the secret death of birds in upsetting the balance of the cosmos?

And that the third Summers brother and uncle of Rachel Gray-Volcano need to do with all this?