One of China's biggest actresses is missing in a real-life mystery that has fans around the globe both perplexed and concerned for her safety.

Fan Bingbing, a 36-year-old Chinese actress known for appearing in hit films like X-Men: Days of Future Past (2014) and I Am Madame Bovary (2016) and topping Forbes’ China Celebrity 100 list four years in a row, has been MIA for months, The Huffington Post reports.

Fan was last seen visiting a children's hospital in early July. After that, she wasn't seen in public. She was, however, active on Weibo, China's major social networking app on which she has more than 62 million followers—until July 23, when she went completely silent. Since then, the actress has not been seen or heard from.

Further down the rabbit hole we go: Her high-profile fiancé, actor Li Chen, was spotted without his engagement ring in August, and reports allege that even billboards and posters featuring the A-list star's name and likeness have been removed all across China, adding an ominous air to her sudden disappearance from the public eye.

In light of Fan Bingbing's vanishing act, a number of frightening theories have emerged.

Weeks before her early July public appearance, retired TV host Cui Yongyuan covertly accused the actress of evading her taxes by manipulating her statement of earnings to the Chinese government, resulting in an inquiry from China's State Administration of Taxation. Cui later apologized and Fan's representative denied the allegations. No formal charges have been announced.

Even more eerie, last week, the Chinese government released an annual report on their national celebrities, revealing that Fan scored a 0% on their "social responsibility" ranking, perhaps an indication of her current less-than-stellar standing in the Chinese government's eyes.

Many now believe that the star was secretly arrested in China and is being detained, but there's been no formal news released from either the Chinese government or Fan's representation. However, in early September, a state-run paper ran a story that Fan was indeed arrested and that the actress was "under control and about to receive legal judgment."

The article was removed hours later, with no retraction or explanation.

Fan recently finished filming Cellphone 2, and is attached to 335, a spy thriller being produced by Jessica Chastain. Fan was in Cannes earlier this year to promote the upcoming movie, which is currently in production. It's unclear if Fan will still be participating in the film, however, as her whereabouts are still unknown.

12 Celebrities With Horrifying Stalker Stories