We already know that Desperate Housewives is crossing over a bit with Castle this spring, as Dana Delany guest stars on the latter show as a federal agent.

It's now been confirmed that she'll be bringing a former Hero along with her.

Leonard Roberts - who starred on the first, actually solid season of Heroes as D.L. - has been cast as the partner of Delany’s character.

On the two-part installment, these two agents are brought in to help Castle and Beckett on a serial killer case. The first half of the episode airs on Sunday night, March 21; while the second half will wrap up the storyline the very next evening, in Castle’s regular time slot.

Meanwhile, encouraged by Castle’s season-high ratings this week, ABC has increased the drama’s episode order from 22 to 24.

Its next new episode, which guest stars Joe Torre and Ray Wise, airs on February 8.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.