The film picks up where the first installment left off, with Frodo and Sam embarking on a perilous journey to destroy the One Ring in the fires of Mount Doom. Meanwhile, Aragorn (Viggo Mortensen), Legolas (Orlando Bloom), and Gimli (John Rhys-Davies) form an alliance to rescue Merry (Dominic Monaghan) and Pippin (Billy Boyd) from the clutches of the evil forces of Saruman.