WARNING: The following contains spoilers for The Vault, now streaming on Netflix.
The Vault ends on an intriguing note as Thom (Freddie Highmore) and his team learn the truth about the mission they've been on, which included them robbing the Bank of Spain to get three coins that belonged to Sir Francis Drake. They then discovered the real haul, according to the coins, is below the Bank of England, thus setting up a sequel.
There are many routes this could go, including the following.
Thom, Walt and Co. Take on England
The Spain heist takes place during the 2010 World Cup, with the crowded streets helping the heroes escape. A disguised Lorraine's then spotted at the London bank during the 2012 Olympics, suggesting the mission's going to once more use a global event and the crowds to help Thom, Walt and co. From here, they can recruit more thieves for the job, making this a growing franchise akin to Ocean's Eleven. Walt has many contacts, who even helped him make fake coins, while Lorraine, Klaus and Simon might also have people in mind. Thom could even bring in other genius students to help engineer the operation.
Spain Goes After Drake's Treasure
The Spanish government believes this treasure is theirs, which is why they seized it from Walt in the first place. Drake, a privateer for the British Crown, sunk a Spanish ship centuries ago and stole it for himself, so they'll want the coins back. It'll be for the archeological value, and if they learn about the fabulous treasure, they'll claim that too.
The Madrid bank could then send Gustavo, a military chief who got duped by Thom's crew, on a hunt as they collect the faces of some of the thieves from cameras. Interpol can aid the Spaniards in tracking these thieves down when they prep for the English job, and Gustavo can hire crooks of his own to help. Meanwhile, some of Walt's competitors may cut deals so they can all benefit as well.
James and Margaret Pursue Thom and Co.
Walt screwed James and Margaret over as they tried to steal the coins from him. As such, they may send MI6 agents over with other thieves for a new smash-and-grab. It'll be personal, as James worked with Walt for years on salvages, while Margaret and Walt seemed to have a romantic and professional relationship at some point.
This can result in a hunt along the lines of National Treasure, with the British wanting Drake's loot to get one over the Spaniards and Walt. Drake screwed them too, so they feel their claim is justified. Ultimately, it's a game of revenge and greed, which will test Thom. Seeing as he and Lorraine may be moving forward as a couple, all these unpredictable moving parts could provide an even greater challenge in a sequel to The Vault, with the first movie now streaming on Netflix.