Ultimate Fantastic Four #50

Thanos returns as a new story arc begins in our fateful 50th issue! The F.F. return from Siberia to find the Baxter Building-and the rest of New York City-under siege! The prize is the greatest force in existence-the Cosmic Cube! And in the race to command this deadliest of weapons, treachery and overkill are the order of the day...even from former friends!