Spider-Man star Tom Holland is known to let secrets slip, but the 21-year-old actor says he has "no idea" about the plot of the upcoming Avengers: Infinity War.

On the train Standing behind two guys debating the plot of avengers. No good asking me lads I have no idea. #AvengersInfinityWar

— Tom Holland (@TomHolland1996) December 4, 2017

"On the train standing behind two guys debating the plot of Avengers," Holland wrote on Twitter. "No good asking me lads, I have no idea."

Holland "accidentally" revealed the first official poster for Infinity War in a skit video shared to his Instagram. The cheeky video saw Holland unbox a package from Marvel Studios and read from an enclosed letter that — unbeknownst to Holland — exclaimed "CONFIDENTIAL — DO NOT SHARE" on its back, a message Holland was unaware of until it was too late.

Holland's Infinity War co-star Mark Ruffalo, who plays Bruce Banner / the Hulk, is also known for his inability to keep secrets — a fact not overlooked by Holland, who poked fun at the actor on social media. Ruffalo has let slip top secret info about Infinity War deaths and accidentally live-streamed parts of Thor: Ragnarok.

Marvel Studios dropped the first record-breaking Avengers: Infinity War trailer Wednesday, offering fans their first look at Hulk returned to Earth and Spider-Man sporting his new "Iron Spider" costume.

Avengers: Infinity War opens May 4.

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