:I've changed it to "The series is set in the West Wing of the White House—where the Oval Office and offices of presidential senior staff are located—during the...[etc.]" Also, I don't think "presidential senior staff" is capitalized. It's not a proper noun. Generally speaking, we capitalize "President" when using it as a noun (but not always, e.g., "Barack Obama was elected president" is correct, I believe). But, we almost never capitalize it when using it as an adjective (e.g., "presidential motorcade", "he spoke in a manner that was very presidential", etc.); hence, we wouldn't capitalize "presidential senior staff".