April 4th, international broadcasts will debut on 17th of April when both BBC America and Canada's Space air the episode followed by ABC1 in Australia on 18th April. This will be the first full episode to star Matt Smith as the Doctor and Karen Gillan as new companion Amy Pond.
After his explosive regeneration damages his TARDIS, the Doctor crash lands on Earth. Without time to recover from regeneration he meets Amy Pond, clashes with the mighty Face Tendril and has to save the world from the Atraxi, a group of galactic policemen.
BBC Official Synopsis:
The Doctor has regenerated into a brand new man, but danger strikes before he can even recover. With the TARDIS wrecked, and the sonic screwdriver destroyed, the new Doctor has just 20 minutes to save the whole world - and only Amy Pond to help him.