Castle s8E16
Castle s8E16Facebook/ Castle

"Castle" Season 8 has finally brought back Kate and Rick to being normal again, especially after Rick's LokSat confession in episode 15. And now, in episode 16, Esposito's past will come back haunting him as he will face inquiry at work over the blunder of being engaged to a criminal in the past.

CLICK HERE to watch "Castle" Season 8 episode 16 live online. And, CLICK HERE to watch "Heartbreaker" later online.

In episode 15, we saw that an NYPD academy recruit got shot and killed with a gun belonging to a fellow recruit. Kate Beckett then put the remaining members through mock training drill and interrogations to pin down the killer. Meanwhile, Rick Castle told Kate about what he learned in LA about his memory loss and that he knew about the LokSat a year ago. He also confessed that he had his memories erased only to protect Kate.

In episode 16, Kate and Rick will be investigating the murder of an armoured car driver, who may have some connections with Esposito's former lover Sonia. According to the synopsis, Kate and Rick's investigation will take them back to a case that was once handled by Espo years ago. Back then, apparently, he got romantically involved with the accused and never told his colleagues about it.

Now, in "Heartbreaker," he will come clean about it to Kate and Rick and will admit that Sonia was his ex-fiancee. He will play a key role in finding out the truth about the driver's murder as Sonia may again be involved in this case and there's a possibility that Espo may be asked to seduce the woman again to gain information.

The promo of the upcoming episode show that Rick, Kate and Ryan are all shocked after they find out that Espo not only dated a criminal, but was also actually engaged to her once. But Espo confessed that he found out that she was a crook only after they got engaged.

Plot synopsis for episode 16, "Heartbreaker" (via reads: "One of Esposito's old cases is re-examined by Castle and Beckett because of a clue left at a crime scene involving an armoured-car driver's murder."

"Castle" Season 8 episode 16 will be aired Monday, April 4, at 10 p.m. on ABC.