So the FCBD issue has already leaked, and folks is gonna be mad.
The story features a shadowy figure instructing an assassin to go find something. The shadowy figure then travels to a planet he's visited before and kills its champion before collecting a payment from them. This payment is a box o' heads and he gives it to his master Thanos. The assassin is then shown on Earth looking for something and hiding behind some Avengers, some X-Men, and SHIELD.
It's a well written comic, and obviously gorgeous to look at but it's got the Hickman thing where it provides only mysteries with no real clues as to what is going on. I enjoyed it, but it's a weird choice for an FCBD issue.