While there are many shows with a 24th episode in their 5th season, this identifier most prominently refers to the of the action-thriller series 24 , titled "Day 5: 6:00 a.m. – 7:00 a.m." Season 5, Episode 24: "Day 5: 6:00 a.m. – 7:00 a.m."
If you were referring to a different series, here are summaries for other popular shows with a 24th episode in Season 5: Grey's Anatomy Season 5 Episode 24 Discussion - Facebook
: Just as Jack Bauer begins to find a moment of peace at an industrial site, he is ambushed and kidnapped by Chinese agents. The season ends with a battered Jack on a boat heading toward China, a consequence of his earlier raid on the Chinese Consulate. Other Notable S5E24 Write-ups
The finale of Season 5 is widely considered one of the series' most high-stakes and emotional hours.