The Plot Thickens $20.00 Inside Message Blank Inside Packages of Heartstrings® cards are shrink-wrapped and sold in sets of 10 cards with envelopes. The actual card size is 4 1/4" x 5 1/2". The Plot Thickens quantity Add to cart SKU: 131. Categories: Baby - Parenting, Gardening, Hearts. Related Products Baby with bike trailer $20.00 You Have Learned to Make Friends $20.00 Mind over motor $20.00 Giving is Receiving $20.00