Like the concern illustrated in N.C. Wyeth’s famous “Go, Dutton, and That Right Speedily” painting for the Robert Louis Stevenson novel “Black Swan,” the FBI has elevated the urgency behind finding that and another stolen Wyeth painting.

Up to $20,000 has been posted as reward money for tips leading to the recovery of the stolen paintings, which were part of a group of six taken from a home in Maine in 2013. Four of them, together worth $2 million, were recovered last December in a Beverly Hills pawn shop, according to a Delaware Public Media report.

The other missing artwork is the Chadds Ford painter’s “The Encounter on Freshwater Cliff,” a piece done for “Westward Ho” by Charles Kingsley.

“They’re filled with action, they’re filled with romance and drama, and from 1911 to 1925, he was at his prime,” Brandywine River Museum of Art Curator Christine Podmaniczky said of Wyeth and his work in the article. “… It really would be a shame if they’re never recovered.”

The man caught illegally transporting the four recovered paintings was convicted just last month.

“The timing of the reward suggests that the trail may have run cold on the two remaining paintings,” the report stated.

Read more about the paintings and their $20,000 bounty on Delaware Public Media here.