Comic book shoppers in Boston just got the surprise of a lifetime. In a new video sponsored by Omaze, "Captain America" himself Chris Evans surprised fans at Comicazi in Somerville, MA by lending his voice to a Captain America doll that led them through a series of challenges to uncover "a Hydra base."

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The video follows three separate groups of people, who are surprised to hear the doll directly address them. Speaking through the doll, Evans tells each group that he needs their help, before guiding them through the store to find clues that will lead them to the secret Hydra base. Of course, none of these participants are aware that Evans is the man behind the doll, so they're in for a pretty huge surprise when they finally do uncover the Hydra base.

As fun as the video is, it isn't just for laughs. The video promotes Omaze's latest contest, which boasts a guest appearance by -- you guessed it -- Evans himself. The winner of the contest and three of their friends will join Evans in an Escape the Room challenge in downtown Boston. Additionally, Evans will take the winner and their friends out for burgers and beer afterward. The winner will be put up in a 4-star hotel for the duration of their stay.

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In order to enter the contest, you must pay for your entries. $10 will get you 100 entries, $25 gets you 250, and so on and so forth. All proceeds will go to Christopher's Haven, which offers apartments to the families of children with cancer who are being treated at MassGeneral Hospital.

According to the Omaze's official contest description,

From stealing the answers to the SAT in The Perfect Score to fighting his way through a train of horrors in Snowpiercer, when it comes to escape, few have more experience than Chris Evans. Now, Chris is inviting you and three friends to join him in what could be one of his most action-packed adventures yet: a custom escape room. You could solve a murder, get locked up in a haunted house, rob a bank or maybe even solve a murder in a haunted bank. No matter the narrative, it’s going to be a night you’ll never forget, complete with scares, laughs, and celebratory burgers and beer. Flights and hotel are on us.

Christopher’s Haven operates a supportive community consisting of nine temporary apartments and a community recreation area for families of children being treated for cancer in nearby Boston hospitals. Over 300 families to date have stayed in the fully-furnished and equipped apartments located across the street from Massachusetts General Hospital. The Loft is utilized to provide programming for children undergoing outpatient treatment, as well as their siblings and parents. Activities coordinated primarily by volunteers, include massage therapy, pet therapy, arts & crafts, movie nights, birthday and holiday parties, bell-ringing ceremonies, outings to sporting events and excursions to local attractions.

Evans will appear as Captain America in “Avengers: Infinity War,” which opens May 4, 2018 and features a sprawling ensemble cast that’s so far confirmed to include Robert Downey Jr., Mark Ruffalo, Chris Pratt, Jeremy Renner, Benedict Cumberbatch and Brie Larson, among others.