Shutter Island, which stars Leonardo DiCaprio as a U.S. marshal investigating a patient's escape from a mysterious asylum on a Massachusetts island, pulled in another $22.2 million, bringing it's overall total to $75.1 million.
The flick held off strong debuts from Kevin Smith's Bruce Willis-Tracy Morgan buddy-cop movie, Cop Out, which hauled in $18.6 million to take second place for the weekend. Also debuting strong: The Crazies ($16.5 million). The remake of George Romero's 1973 horror film took third place.
Avatar came in at No. 4, adding another $14 million to its total, which now stands at $706.9 million. The overall box office for the weekend stood at $120 million, a 7 percent increase over the same weekend a year ago.
Rounding out the top 10: Percy Jackson & the Olympians: The Lightning Thief ($9.8 million), Valentine's Day (2010) ($9.5 million), Dear John (2010) ($5 million), The Wolfman ($4.1 million), Tooth Fairy ($3.5 million) and Crazy Heart ($2.5 million).