After five (or six) years of vanilla-wedded bliss, ordinary suburbanites John and Jane Smith are stuck in a huge rut. Unbeknownst to each other, they are both coolly lethal, highly-paid assassins working for rival organisations. When they discover they're each other's next target, their secret lives collide in a spicy, explosive mix of wicked comedy, pent-up passion, nonstop action and high-tech weaponry.

Eccentric consulting detective Sherlock Holmes and Doctor John Watson battle to bring down a new nemesis and unravel a deadly plot that could destroy England.