|--story [1]-|
   ---[a]------------[b]----[c]---------[d]---[e]-
   jan feb mar apr may jun jul aug sep oct nov dec
   -----------------------------------------------
   ---[2]------|                           |--[2]-

Cases:
[a] ends_at > today,
    ends_at < starts_at

[b]

[c] starts_at < today,
    ends_at > today,
    starts_at < ends_at

[d]

[e] starts_at < today
    starts_at > ends_at