Highlights 5/16 to 5/22

Scientific and medical communities have discovered that the horseshoe crab provides an indispensable testing agent for drugs and vaccines, as well as resources for human optics and burn treatment. But horseshoe crab numbers are plummeting, as told by Nature on Sunday at 7 p.m.

In a case that will shatter his personal world to the core on Masterpiece Mystery, the newly retired Foyle battles to save a young man accused of high treason from the executioner’s noose at 8 p.m. Sunday.

The Battle of Gettysburg was the turning point of the war on The Civil War at 8 p.m. Monday.

Nova presents a minute-by-minute eyewitness account of the Hurricane Katrina disaster, exploring why the flood defenses and disaster relief planning failed to match Katrina’s fury at 7 p.m. Tuesday.

Frontline tells the dark tale of the men of Third Platoon and how the war followed them home. It is a powerful portrait of what multiple tours and post-traumatic stress are doing to a generation of young American soldiers at 8 p.m. Tuesday

Two young American women, one Muslim, the other Hindu, sneak their cameras into Kashmir, where conflicting faiths mean war on Independent Lens at 9:30 p.m. Tuesday. Their mission: to find out what makes their peers choose homeland over preserving their own lives.

Secrets of the Dead: Deadliest Battle tells the true story of the battle that turned World War II, and established the Soviet Union as a world superpower for the looming Cold War at 7 p.m. Wednesday.

Rockers Pearl Jam take the Austin City Limits stage with tunes from their latest album, Backspacer, as well as catalogue favorites at 10 p.m. Wednesday and 9 p.m. Friday.

Episcopal Bishop of Texas Andrew Doyle talks about new media and the church on Texas Monthly Talks at 7 p.m. Thursday and 8:30 p.m. on Friday.

Through behind-the-scenes archival and rare footage, photographs and first-person accounts, Cinema’s Exiles: From Hitler to Hollywood traces the experiences of the exiles who took refuge in Hollywood and examines their impact on both German and American cinema at 8 p.m. Thursday.

Rock superstars the Dave Matthews Band lights up Austin City Limits with hits and songs from their latest album Big Whiskey and the GrooGrux King at 7 p.m. Saturday.