When John Prince bribes a pharmaceutical magnate to cut off Sherwood's medical supplies, he threatens Tressie's delicate health and drives Robyn and The Hood to a daring heist.

Lionheart Day kicks off with a surprise as John Prince offers to bargain with Tressie over Sherwood's future; while Tressie and Prince negotiate, Robyn starts to suspect things are not what they seem when Guy Gisbourne returns to crash the party.