Diane Haithman contributes to Deadline’s TCA coverage.

At today’s TCA panel on ABC’s new drama series Once Upon a Time in Wonderland, the producers said the initial order of 13 episodes will “tell a complete story.” If the show returns, said executive producer Adam Horowitz, “we will come back with another adventure.” In describing the relationship of Wonderland to the series Once Upon a Time (which introduced some elements that are part of the new series), Horowitz said Wonderland “exists in a Once universe but stands on its own. The pilot hits the ground running, [new viewers] can come right in.”

EP Edward Kitsis called the new drama a “psychedelic romance.” The new show begins filming this week on the same set as Once, producers said. The cast of characters that Alice (Sophie Lowe) might meet in Wonderland naturally lends itself to guest stars doing voices. The producers confirmed that John Lithgow’s White Rabbit of the pilot will be a regular character, not a cameo. The Who’s Roger Daltrey will be the voice of the hookah smoking Caterpillar and producers are seeking a Cheshire Cat. As the series progresses other characters will “pop up with great voice actors behind them,” producers said.

Sebastian Stan, who has recurred on Once Upon a Time as the Mad Hatter but couldn’t do the Wonderland pilot, probably won’t recur in the series “because his schedule is so packed,” said Horowitz. “We would move heaven and earth to have him come back on either show, but he’s doing Captain America now … he has an open door.” The producer added that whether or not Stan becomes available in the future: We are never going to have a Mad Hatter who is NOT played by Sebastian.”

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