When Castle returns from a mini hiatus on April 16, we'll be treated to the appearance of Adam Baldwin as a temporary new partner for Rick.

But TV Line has the scoop on an even more exciting guest star scheduled for the May 7 season finale, mostly due to what it will mean on a grander scale for Kate Beckett.

Judith Scott will reportedly reprise the role of Captain Montgomery's wife on that installment. What is Evelyn doing back in the picture?

Castle creator Andrew Marlowe simply says her presence is related to an ongoing investigation that could be "linked to Beckett's mother murder case." Oh, yes, Marlowe says, the series will pick "at that stab again."

Four new episodes remain this season. Check out the video above for an early look at what's to come and then sound off on this season finale spoiler!