Keir Starmer assumes the role of Prime Minister in the UK, facing traditions like being clapped into 10 Downing Street and the sobering responsibility over nuclear missiles. Larry the Cat, a symbol of stability, continues his tenure as Chief Mouser, welcoming the new PM. Amid political shifts, Larry's authority is highlighted as Rishi Sunak resigns pending Starmer's appointment. As Starmer's family, including pets like Jojo, move in, the dynamics with Larry, who is not owned but serves as Chief Mouser, remain uncertain.