5 Things to Know This Morning

— -- Your look at the five biggest and most buzz-worthy stories of the morning.

1. What It’s Like to Be Married to a Convicted Killer on Death Row

Rosalie and Oscar Bolin have been married for 18 years. Oscar sends her love letters and hand-drawn cards practically every day, and Rosalie has kept them all.

“I couldn’t bear to throw any of them away. I couldn’t. I think the art of love making is probably in these cards,” Rosalie Bolin told ABC News' "20/20."

But the couple has never lived together. In fact, they are only allowed to see each other twice a week. That’s because Oscar lives on death row at Florida State Prison in Raiford, Florida.

2. North Korea Warns of War After Exchange of Fire With South

North Korean leader Kim Jong Un on Friday declared his frontline troops in a "quasi-state of war" and ordered them to prepare for battle a day after the most serious confrontation between the rivals in years.

South Korea's military on Thursday fired dozens of artillery rounds across the border in response to what Seoul said were North Korean artillery strikes meant to back up a threat to attack loudspeakers broadcasting anti-Pyongyang propaganda.

3. Hero Surfer Helps Rescue Teens from Lake Michigan Rip Current, Officials Say

A hero surfer helped pluck two teenage girls from what appeared to be a rip current in Lake Michigan, officials said.

Zeb Boeskool sprung into action after the girls were spotted approximately 800 feet out from the pier in Grand Haven, about 15 miles from Muskegon.

"It appears that the girls may have become caught in a rip current," Jeff Hawke, the Grand Haven Public Safety Director, said in a statement.

4. Nazi 'Ghost' Train Loaded With Gold, Treasure May Have Been Found, Polish Officials Say

A Nazi "ghost" train full of looted gold, gems and other treasures vanished after entering a secret system of tunnels as the Germans fled advancing Soviet forces near the end of World War II, according to local lore in Poland.

The train's existence has never been confirmed by historians, but it may actually be real, according to Polish officials who said that two men claim to have found it.

"We believe that a train has been found," Marika Tokarska, the district governor of a southwestern Polish district of Walbrzych, told the Associated Press. "We are taking this seriously."

5. Woman Finds Mysterious Urns in Used Car She Bought at Auction in Washingtonc

A Bonney Lake, Washington, woman recently discovered four mysterious urns inside a used SUV she bought at an abandoned car auction.

The woman, Andrea Davidson, told ABC News she bought the teal 1997 Geo Tracker for about $700 last week at Pro-Town in Auburn, Washington. When she took it home to check its condition, she was "shocked" at what she found, she said.