The title of the television series is taken from W, a fictional webtoon which became a bestseller in South Korea. Authored by Oh Seong-moo, the webtoon became a living universe, engendering "two worlds": the real world and the webtoon or Wworld. The gap between the two worlds is closed as Seong-moo's daughter and resident cardiothoratic surgeonOh Yeon-joo (Han Hyo Joo) gets dragged into the webtoon world, inciting a series of twisted events.
The webtoon world of W is an approximate replica of the real world South Korea and its capital Seoul. Entry to the webtoon world can be through Seong-moo's magical tablet, or upon a summoning from the webtoon world or from W's main character Kang Chul (Lee Jong Suk). On the other hand, reentry (though teleportation) to the real world happens also upon Kang Chul's or the webtoon's bidding, or through a rectangular, crystal-like portal, which appears once Kang Chul discovers and affirms to himself the truth behind his world and his identity as the main cartoon character. Once the story of the webtoon ends, the webtoon world continues to exist but the "characters" will instantaneously lose their titles as "characters" and may live their own lives.
