Stingray (1964)

S1E16 The Lighthouse Dwellers

Chaos ensues when a pilot attempting to land at a newly opened airfield crashes after being distracted by the unexpectedly lit beacon of an abandoned lighthouse. The former keeper, returning to inspect the situation, is taken hostage by an extraterrestrial species that harnesses the lighthouse's energy to fuel their metropolis. It's up to the Stingray crew to rescue the lighthouse keeper and ensure the city's survival against the alien threat.