In tonight's episode of Merlin, "The Hunter's Heart," Morgana plots a siege on Camelot while the kingdom, and Arthur, are preoccupied by the arrival of Mithian (Janet Montgomery of Human Target), the beautiful princess with whom the young king has pledged to form both a political and romantic alliance. However, Merlin suspects Arthur's heart is still broken over his banishment of Guinevere.

In this SPINOFF-exclusive scene, Gwen (Angel Coulby), now the captive of the warlord Helios (Terence Maynard), eavesdrops as he conspires with Morgana (Katie McGrath) to attack Camelot.

Merlin airs tonight at 10 ET/PT on Syfy.