'Supernatural' Season 10 Spoilers: Castiel, Dean and Sam Face Off With the Ultimate Monster

Season 10 episode 20 of "Supernatural" will be aired on The CW at 9.00 pm (EST) on Wednesday, 29 April.

The upcoming episode, titled "Angel Heart" will take a short detour from the show's current journey towards Dean's imminent destruction. According to the promo for "Angel Heart", the Winchester boys will be led by a heavenly assassin to the ultimate monster: a teenage girl.

The said monster is none other than Claire Novak (Sydney Imbeau), the biological daughter of Jimmy Novak (Misha Collins), whose body Castiel is now possessing. She last appeared in season 10 episode 10 "The Hunter Games", wherein the troubled teenager tells Castiel that she does not trust him, especially because his loyalty lies with Dean (Jensen Ackles).

In episode 20, Claire is back because she has a lead on where her mother Amelia (Leisha Hailey) is, and Cas, who feels responsible for ripping apart the Novak family decides to help her. Cas, who isn't very adept in dealing with teenage girls, calls the Winchesters for back-up.

Although Dean and Claire have never gotten along in the past, he and brother Sam (Jared Padalecki) agree to help Claire. However, they soon realise that Claire may never get a happy ending, when they find out what took Amelia away.