Watch Half Dozen Previews for Martian Manhunter Episode on 'Supergirl'

Monday's 'Supergirl' episode gives viewers some insight on the Martian Manhunter's backstory. There'll be plenty of flashbacks where J'onn J'onzz (David Harewood) meets Kara's dad, Jeremiah (Dean Cain), and her sister Alex (Chyler Leigh) for the first time.

Winn (Jeremy Jordan) tries to comfort his girlfriend(?) Siobhan Smythe (Italia Ricci) after Cat fires her. Angry and drunk, Siobhan plots her revenge against Kara leading to her ultimate transformation into the villain Silver Banshee. 

Elsewhere, Cat tries to reconcile Supergirl's plummeting public image after she went rogue thanks to red kryptonite last week. Crime is on the rise and it's up to Kara to gain the public's trust again. 

'Supergirl' airs "Manhunter" episode MondaY at 8 p.m. on CBS

J'onn J'onzz reveals the details of meeting Kara and Alex’s father, Dr. Jeremiah Danvers (Dean Cain), and assuming Hank Henshaw's identity. Also, Kara debates trusting someone new with her secret identity and Siobhan (Italia Ricci) plots against Kara, on Supergirl, Monday, March 21 at 8/7c. Only CBS