"Children of Beslan: The Russian School Siege" (8 p.m., HBO): This documentary that marks the one-

"Children of Beslan: The Russian School Siege" (8 p.m., HBO): This documentary that marks the one-year anniversary of the siege in which Chechen rebels stormed a school and held hostage more than 1,000 children and adults in a gym for three days, denying them water. The siege ended 57 hours later in a hail of gunfire that killed 331 people. The film includes footage taken by the extremists and interviews with more than a dozen of the children, ages 6 to 12, some of whom are now orphans.
"Being Bobby Brown" (10 p.m., Bravo): A marathon recounts all the moments when Bobby and wife Whitney Houston are sober.
"The O.C." (8 p.m., Fox): The seaside soap's third season is marked by the reunion at last of teenage lovers Summer Roberts (Rachel Bilson) and Seth Cohen (Adam Brody), who come together after a roller-coaster season of complications and plot twists.