Movie Version: The Secret of the Diary reveals:

Officially, as Biographer of the Tomb Raider would say, our young Lara travels to Hong Kong where she hires Lu Ren, captain of the ship Endurance, to sail into the Devil's Sea and the island of Yamatai.

The ship capsizes in a violent storm and Lara has washed ashore where she is knocked ****. She awakens only to encounter Mathias Vogel, the leader of an expedition to locate Himiko's tomb. The expedition has been funded by a shadowy organization called Trinity, which seeks to harness and weaponize Himiko's power. Vogel takes Lara prisoner, claiming that he killed her father and revealing that he intends to use Richard's research to continue his expedition. He adds Lara and Lu Ren to his **** ****; eventually, the two of them try to escape, and Lara is the only one successful.

However, what truly happened to Lara after her captivity and before her escape was a secret that the huntress could only entrust to her secret diary of lust and shame.

In Truth, young Lara has spent three weeks on that cursed Island. And she asked her friend Lu Ren to keep this as a secret, never asking why. With the loyal Lu Ren, all of the people who knew the truth were gone, and only Lara and her diary were left.