Some convoluted films culminate with a confessional speech, an expository epilogue, or a different method of clarifying what just went down. Others leave viewers with furrowed eyebrows, a racing brain, and the inclination to hop on the internet and hunt for their own answers.

By analyzing search data for film titles paired with terms like explanation, breakdown, meaning, plot, and ending explained, UK-based online retailer OnBuy.com compiled a list of 18 movies that utterly puzzled—and continue to bewilder—audiences. Most of the films are science fiction, psychological thrillers, or some combination of the two, with a few neo-noir mysteries and metaphysical dramas thrown in. And if there’s one director known for baffling sci-fi fans, it’s probably Christopher Nolan; an average of 80,090 people ask the internet to explain 2010’s Inception every month, and his films Interstellar and Memento also made the top 10.

Nolan is far from the only repeat filmmaker on the list. Mulholland Drive (2001) and Blue Velvet (1986), both written and directed by David Lynch, leave enough loose ends to send viewers straight to Google, and sisters Lana and Lilly Wachowski landed on the list for 1999’s The Matrix and 2012’s Cloud Atlas. It’s a testament to Stanley Kubrick’s ongoing popularity that 1980’s The Shining and 1968’s 2001: A Space Odyssey—both released decades before the rise of the internet—are still confounding audiences.

Certain actors seem to gravitate toward confusing movies, too. Leonardo DiCaprio starred in the top two films on the list, Inception and Shutter Island (both released in 2010), and Jessica Chastain appeared in both Interstellar and Terrence Malick’s The Tree of Life (2011). Brad Pitt, Carrie-Anne Moss, Hugo Weaving, Michael Caine, and Joe Pantoliano also feature in at least two films below.

Scroll on to see which other movies made the list, along with their average monthly search volumes.

  1. Inception (2010) // 80,090
  1. Shutter Island (2010) // 55,700
  1. The Shining (1980) // 48,950
  1. Interstellar (2014) // 47,060
  1. Ex Machina (2014) // 32,440
  1. Donnie Darko (2001) // 32,310
  1. 2001: A Space Odyssey (1968) // 31,260
  1. The Matrix (1999) // 27,120
  1. Citizen Kane (1941) // 25,480
  1. Memento (2000) // 24,060
  1. Vanilla Sky (2001) // 22,479
  1. Cloud Atlas (2012) // 22,250
  1. 12 Monkeys (1995) // 19,990
  1. Mulholland Drive (2001) // 18,990
  1. Adaptation (2002) // 18,920
  1. The Fountain (2006) // 15,420
  1. Blue Velvet (1986) // 15,380
  1. The Tree of Life (2011) // 14,440