In Skull and Bones, contracts are missions you can take on to earn rewards and progress through the game. However, based on current information and gameplay details, there isn’t a specific contract called "Skull and Bones Ambush Contract."
The "Ambush" narrative you might be referring to is likely part of an in-game activity called "Investigation." In these investigations, players follow clues and complete tasks to uncover the secrets behind various events, such as ambushes and hidden treasures.
The "Ambush" investigation involves:
While not a traditional contract, completing this investigation provides you with rewards like increased reputation, new resources, and potentially, access to hidden locations.
Here are some resources that might be helpful:
I hope this clarifies the information!