A television tradition that has become one of the highest-rated shows on PBS, the National Memorial Day Concert (7 p.m. Sunday, check local listings) airs live from the West Lawn of the Capitol in Washington, D.C. Dignitaries and performers include Gen. Colin Powell, Daughtry, Natalie Cole, Trace Adkins, Ellen Burstyn and Dennis Franz. Once again, Gary Sinise and Joe Mantegna, two actors dedicated to veterans’ causes, will share co-hosting duties.

• As if to salute the summer silly movie season now upon us, Animal Planet offers the speculative documentary “Mermaids: The Body Found” (8 p.m. Sunday).

For starters, the network is not calling this a “real” documentary. Buried deep within its publicity is this telling description: “sci-fi based on some real events and scientific theory.” That’s a rather elastic definition that could very well describe “Jurassic Park.”

”Mermaids” unfolds like your typical conspiracy theory film. The Navy has been testing some new sonar that has disoriented many whales and driven them onshore. This apparently is true. Not so certain are the creatures that may have accompanied them — strange mammals seen by two small boys who described them to neighbors and authorities until they were pressured by government heavies to recant!

The film pivots into a speculative look at man’s long evolutionary hiatus spent underwater and the notion that man- or woman-like sea mammals still dwell in the depths.

”Mermaids” may not convince you of deep-water maidens. But it offers a grab-bag of tabloid-genre tricks, including “found” grainy footage, generic talking-head “experts,” frequent re-enactments, and the blurry image and garbled voice of a “witness” too frightened to come forward.

Sunday’s highlights

• Indianapolis 500 coverage and pre-race festivities (10 a.m., ABC).

• NASCAR racing at the Coca-Cola 600 (4:30 p.m., Fox), live from Charlotte Motor Speedway in North Carolina.

• Scheduled on “60 Minutes” (6 p.m., CBS): a profile of a Medal of Honor recipient, two Marine brothers, help for returning veterans.

• Don’s creative juices are in short supply on “Mad Men” (9 p.m., AMC)

• Controversy on the menu on “Veep” (9 p.m., HBO).