Loki Pays a Debt

Avengers: Infinity War unleashes 8 exclusive new photos

Before the end of Thor: Ragnarok, Tom Hiddleston's Loki managed to pocket the blue Space Stone locked away in Asgard's archive. This is the object Thanos sent him to retrieve in the original Avengers, and he not only failed — he lost the staff that contained the yellow Mind Stone (now giving life to Paul Bettany's Vision). We know Thanos collects the Space Stone early in Infinity War, so Loki has likely settled his account. Partially.  

Entertainment Weekly

MARVEL’S AVENGERS: INFINITY WAR
Tom Hiddleston as Loki