This will sound at first like a Washington Nationals story. It isn’t, or at least not too much. Stick with it.

Twelve-year-old Drew Jackson was at a Nationals game last Tuesday when the Nats’ community relations manager London Hitchman summoned him upstairs to his office. This didn’t strike Drew as weird. Hitchman had been his Little League coach for five years.

Hitchman handed Drew a Nationals tote bag. Inside were three items: a #2 Denard Span Nationals’ jersey and two envelopes. Drew tore open the first envelope that said Clue #1. He found a photo of AT&T Park. He opened Clue #2. It was a photo of an airplane.

Drew had no idea what was going on. He looked at Hitchman, then at his mother Tracie Dow, who broke into a smile. Suddenly Drew remembered what Denard Span had told him when he signed with the Giants: He’d bring Drew out to San Francisco for a game. Drew broke into tears.

Denard had been Drew’s favorite player even before he arrived at the Nationals: Span was a lefty centerfielder just like Drew. They met at Nationals Park four years ago. The son of a single mom, Denard hosted single-parent families at Nationals Park during his three seasons there, a group he called Span’s Fans. Kids and their parents (mostly moms) attended batting practice, met with Denard, then stayed for the game, refreshments included. (Denard also hosts annual events to honor single mothers through his DSpan Foundation.)

Over the years the two communicated through Drew’s mother’s Instagram. They became so connected that when Denard was awarded the Roberto Clemente Award in 2015 and couldn’t attend due to his sports hernia surgery, he sent Drew to accept it in his stead.

On Monday morning, Drew — in his №2 Nationals jersey — reunited with his favorite player in the Giants’ dugout before their game against the Nationals. His mom and grandmother snapped pictures and beamed.

“Hey!’’ Giants coach Shawon Dunston cried as he walked through the dugout. “He’s got the wrong uniform!’’

Denard laughed. “We’re going to let it slide today — because it’s got Span on it.’’ (Soon a Giants’ clubbie emerged with Giants shirts and hats for Drew and his family.)

Before Denard returned to the clubhouse to get dressed for the game, Drew gave him a framed collage of photos the two had taken together over the years. “Thank you, man!’’ Denard said. “This will go on my wall at home.’’

After the game, Denard and his wife, Anne, capped the weekend visit by fetching Drew and his family at the Hilton and taking them out to a steak dinner.