Garrett and the team, assisted by ex-colleague Clara Seger, try to find three missing US volunteers in Bangkok.
Dexter has been losing sleep, which is putting strain on both his daytime job and his night-time fun.
The team runs into big problems when the US embassy is attacked in South Sudan. They need to get everyone out ASAP. But the ambassador has other ideas.
When Castle's idol, a famously reclusive author, turns up dead, Castle is determined to solve his hero's murder, but as he and Beckett dig deeper, they discover that truth is stranger than fiction.
Christy and Bonnie are suspicious when Adam's best friend returns, insisting he's a changed man.