There will be some "complications" between Esposito (Jon Huertas) and Castle (Nathan Fillion) and Beckett (Stana Katic) in the next episode of ABC's Castle.

ABC has released a new plot synopsis for the next episode of Castle, which is titled "Heartbreaker." The synopsis reveals how the new case the team is investigating has some ties to Esposito.

"A clue at the scene of the death of an armored-car driver leads Beckett and Castle back to an old case solved by Esposito," the synopsis reads. "But complications arise when they learn that Esposito might not have been telling them everything about his past with the culprit."

The guest cast for the episode includes Angelica Celaya as Sonia Ruiz, Dean Cudworth as Michael Kirby, Michael Cognata as Darrl Ives and Gonzolo Menendez as Ronaldo.

Celaya's Sonia is the culprit in question, as seen from the promo released this week. Ryan (Seamus Dever) tells Esposito in the promo, "You're a cop, how can you get involved with a criminal?" Castle quips that it's a "workplace romance." We also see a scene with Eposito and Sonia leaning in for a kiss, though it remains to be seen if this is a flashback or a present-day scene.

The series is currently taking a break from new episodes, but "Heartbreaker" will air on Monday, April 4 in its regular time-slot.

In the meantime, Castle fans are patiently waiting for ABC to make a decision on the future of the crime procedural. The network renewed 15 of its series earlier in the month, including stalwarts like Modern Family, Once Upon a Time, Dancing With the Stars and Scandal, but Castle was left off the list.

This may have to do with contract negotiations still not taking place or being finalized for Fillion and Katic. Now that the show has been on for seven seasons, the stars are now negotiating new contracts every year. However, the series is growing older and it remains to be seen if Fillion and/or Katic will want to keep going with it.

Castle airs Mondays at 10 p.m. ET/PT on ABC.

Watch the promo for the next episode of Castle below: