It's 1836 and Lt. Col. William Travis (PATRICK WILSON) has been sent to the Alamo, a former Franciscan mission in San Antonio, Texas, to control what's now an American fort in the Texan war of independence from Mexico.
Joining him is Jim Bowie (JASON PATRIC), a commissioned colonel in the Texan army who doesn't believe Travis is the right man to defend the position. Congressman and frontier legend Davy Crockett (BILLY BOB THORNTON) and his men also arrive on the scene, having been sold on the idea of traveling to Texas by General Sam Houston (DENNIS QUAID).
Little do any of them know that Mexican General Antonio López de Santa Anna (EMILIO ECHEVARRÍA) is leading an Army of thousands to retake the Alamo. With less than two hundred men in the garrison -- including Mexican born Col. Juan Seguin (JORDI MOLLÁ) -- the American forces prepare for the onslaught.
Yet, it doesn't occur right away, leading to a tense standoff between the two military forces. With the Mexican army repeatedly testing the resolve of their opponents and their defense of the Alamo, the much smaller American forces hope that Houston will be able to gather and send reinforcements before it's too late.