Hold up: Castle (Nathan Fillion) is sleeping with both Beckett (Stana Katic) and his ex-wife?

Not exactly, but the trio is definitely too close for comfort when a series of unfortunate events results in both women bunking down in Rick’s apartment!

When “Castle” finally returns Jan. 7, Meredith (Darby Stanchfield, now on “Scandal”), invites herself to Casa Castle to care for Alexis Molly Quinn, suffering from mono. And if a former wife’s reappearance isn’t enough stress on a couple’s new romance, Kate is forced to share their quarters while her apartment is being fumigated. Worst. Timing. Ever.

As Esposito warns in the video below, “That’s like throwing gasoline on fireworks!”

The episode, aptly titled “Significant Others,” also features a nasty dispute between two other exes — played by soap stars Nancy Lee Grahn (“General Hospital”) and Jack Wagner (“Melrose Place” and “GH”), hamming it up to soapy perfection.

“Castle” returns Monday, Jan. 7 at 10 p.m. on ABC.

Posted by:dmoorhouse